Merge branch 'current' of https://github.com/cwiki-us-docs/java-tutorials into HEAD

# Conflicts:
#	.gitignore
#	.idea/compiler.xml
#	.idea/encodings.xml
#	.idea/vcs.xml
#	pom.xml
#	src/main/java/com/ossez/lang/tutorial/overview/HelloWorld.java

src/main/java/com/ossez/lang/tutorial/Main.java

@@ -0,0 +1,91 @@
+package com.ossez.lang.tutorial;
+
+import java.util.Properties;
+
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.CommandLineParser;
+import org.apache.commons.cli.GnuParser;
+import org.apache.commons.cli.Options;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Main {
+	private static final Logger logger = LoggerFactory.getLogger(Main.class);
+
+	private static Options options = new Options();
+	private static Properties properties = new Properties();
+
+	private static CommandLine cl = null;
+
+	private static boolean dryRun = false;
+	private static int limit = 0;
+	private static boolean force = false;
+
+	public static void main(String[] args) {
+
+		// get the idx feed properties file
+		Main.parseProperties();
+
+		// load console options
+		Main.parseCommandLine(args);
+
+		logger.debug("Starting feeds...");
+		System.out.println("starting feeds...");
+
+		// execute the feeds
+		Main.executeFeeds();
+
+	}
+
+	/**
+	 * Executes the feeds specified in the feeds.properties file.
+	 */
+	private static void executeFeeds() {
+
+	}
+
+	/**
+	 * Parses the properties file to get a list of all feeds.
+	 */
+	private static void parseProperties() {
+		try {
+			// load the properties file
+			logger.debug("Parsing properties");
+			Main.properties.load(Main.class.getClassLoader().getResourceAsStream("rets.properties"));
+
+			// load the feeds
+
+		} catch (Exception ex) {
+			ex.printStackTrace();
+			logger.error("Could not parse feed properties", ex);
+		}
+	}
+
+	/**
+	 * Handles creation of console options.
+	 */
+	private static void parseCommandLine(String[] args) {
+
+		// parse command line options
+		CommandLineParser parser = new GnuParser();
+
+		try {
+			Main.cl = parser.parse(Main.options, args);
+
+			// get the dry run option
+			Main.dryRun = Main.cl.hasOption("d");
+			logger.trace("Value of dryRun: " + dryRun);
+
+			// get the limit option
+			// Main.limit = Utility.parseInt(Main.cl.getOptionValue("l", "0"));
+			logger.trace("Value of limit: " + Main.limit);
+
+			// get the force option
+			Main.force = Main.cl.hasOption("u");
+			logger.trace("Value of force: " + Main.force);
+		} catch (Exception ex) {
+			logger.error("An error ocurred parsing command line arguments", ex);
+		}
+	}
+}

src/main/java/com/ossez/lang/tutorial/models/ListNode.java

@@ -0,0 +1,16 @@
+package com.ossez.lang.tutorial.models;
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class ListNode {
+	public  int val;
+	public  ListNode next;
+
+	public ListNode(int x) {
+		val = x;
+		next = null;
+	}
+}

src/main/java/com/ossez/lang/tutorial/models/TreeNode.java

@@ -0,0 +1,16 @@
+package com.ossez.lang.tutorial.models;
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class TreeNode {
+	public int val;
+	public TreeNode left, right;
+
+	public TreeNode(int val) {
+		this.val = val;
+		this.left = this.right = null;
+	}
+}

src/main/java/com/ossez/lang/tutorial/objplusclass/CreateObject.java

@@ -0,0 +1,18 @@
+package com.ossez.lang.tutorial.objplusclass;
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class CreateObject {
+	public CreateObject(String name) {
+		// This constructor has one parameter, name
+		System.out.println("小狗的名字是: " + name);
+	}
+
+	public static void main(String[] args) {
+		// Following statement would create an object myPuppy
+		CreateObject myPuppy = new CreateObject("Tomcat");
+	}
+}

src/main/java/com/ossez/lang/tutorial/overview/FreshJuiceEnums.java

@@ -0,0 +1,22 @@
+package com.ossez.lang.tutorial.overview;
+
+/**
+ * Java Tutorial
+ * 
+ * @author YuCheng
+ *
+ */
+class FreshJuice {
+	enum FreshJuiceSize {
+		SMALL, MEDIUM, LARGE
+	}
+
+	FreshJuiceSize size;
+}
+
+public class FreshJuiceEnums {
+	public static void main(String[] args) {
+		FreshJuice juice = new FreshJuice();
+		juice.size = FreshJuice.FreshJuiceSize.MEDIUM;
+	}
+}

src/main/java/com/ossez/lang/tutorial/overview/HelloWorld.java

@@ -3,11 +3,25 @@ package com.ossez.lang.tutorial.overview;
 /**
  * Java Tutorial
  * 
+<<<<<<< HEAD
+=======
+ * This is my first java program. This will print 'Hello World' as the output This is an example of multi-line comments
+ * 
+>>>>>>> 361e407d91e00158295aadeaca0a91d84a534820
  * @author YuCheng
  *
  */
 public class HelloWorld {
 	public static void main(String[] args) {
+<<<<<<< HEAD
 		System.out.println("Hello World");
 	}
-}
+}
+=======
+		// This is an example of single line comment
+		/* This is also an example of single line comment. */
+
+		System.out.println("Hello World");
+	}
+}
+>>>>>>> 361e407d91e00158295aadeaca0a91d84a534820

src/main/java/com/ossez/lang/tutorial/usecases/VarargsCase.java

@@ -0,0 +1,37 @@
+package com.ossez.lang.tutorial.usecases;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * variable arguments use case
+ */
+public class VarargsCase {
+    private static final Logger logger = LoggerFactory.getLogger(VarargsCase.class);
+
+    /**
+     * sumVarargs
+     *
+     * @param intArrays
+     * @return
+     */
+    static int sumVarargs(int... intArrays) {
+        int sum, i;
+        sum = 0;
+        for (i = 0; i < intArrays.length; i++) {
+            sum += intArrays[i];
+        }
+        return (sum);
+    }
+
+    /**
+     * Main Function
+     *
+     * @param args
+     */
+    public static void main(String args[]) {
+        int sum = 0;
+        sum = sumVarargs(new int[]{10, 12, 33, 7});
+        logger.debug("The Sum of the arrays: {}", sum);
+    }
+}

src/main/java/com/ossez/lang/tutorial/utils/TreeUtils.java

@@ -0,0 +1,55 @@
+package com.ossez.lang.tutorial.utils;
+
+import java.util.ArrayList;
+
+import com.ossez.lang.tutorial.models.TreeNode;
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class TreeUtils {
+
+	public static TreeNode initTree(String data) {
+		// NULL CHECK
+		if (data.equals("{}")) {
+			return null;
+		}
+
+		ArrayList<TreeNode> treeList = new ArrayList<TreeNode>();
+
+		data = data.replace("{", "");
+		data = data.replace("}", "");
+		String[] vals = data.split(",");
+
+		// INSERT ROOT
+		TreeNode root = new TreeNode(Integer.parseInt(vals[0]));
+		treeList.add(root);
+
+		int index = 0;
+		boolean isLeftChild = true;
+		for (int i = 1; i < vals.length; i++) {
+			if (!vals[i].equals("#")) {
+				TreeNode node = new TreeNode(Integer.parseInt(vals[i]));
+				if (isLeftChild) {
+					treeList.get(index).left = node;
+				} else {
+					treeList.get(index).right = node;
+				}
+				treeList.add(node);
+			}
+
+			// LEVEL
+			if (!isLeftChild) {
+				index++;
+			}
+
+			// MOVE TO RIGHT OR NEXT LEVEL
+			isLeftChild = !isLeftChild;
+		}
+
+		return root;
+
+	}
+}

src/main/resources/log4j2.xml

@@ -0,0 +1,97 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE RelativeLayout>
+<Configuration status="WARN">
+
+	<Properties>
+		<Property name="baseDir">/home/logs/reoc/services/</Property>
+	</Properties>
+
+	<Appenders>
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- C O N S O L E - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<Console name="CONSOLE" target="SYSTEM_OUT">
+			<PatternLayout pattern="%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n" />
+			<ThresholdFilter level="TRACE" onMatch="ACCEPT" onMismatch="DENY" />
+		</Console>
+
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- D E B U G _ F I L E - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_DEBUG" append="true" fileName="${baseDir}/services_debug.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-debug-%d{yyyy-MM-dd}-%i.log.gz">
+			<ThresholdFilter level="DEBUG" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- I N F O _ F I L E - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_INFO" append="true" fileName="${baseDir}/services_info.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-info-%d{yyyy-MM-dd}.log.gz">
+			<ThresholdFilter level="INFO" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+		
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- F I L E _ W A R N - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_WARN" append="true" fileName="${baseDir}/services_info.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-warn-%d{yyyy-MM-dd}.log.gz">
+			<ThresholdFilter level="WARN" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+		
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- F I L E _ E R R O R - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_ERROR" append="true" fileName="${baseDir}/services_error.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-error-%d{yyyy-MM-dd}.log.gz">
+			<ThresholdFilter level="ERROR" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+	</Appenders>
+
+	<!-- LOGGERS -->
+	<Loggers>
+
+		<Logger name="com.ossez" level="TRACE" additivity="false">
+			<AppenderRef ref="CONSOLE" level="DEBUG" />
+			<AppenderRef ref="FILE_DEBUG" level="DEBUG" />
+			<AppenderRef ref="FILE_INFO" level="INFO" />
+			<AppenderRef ref="FILE_WARN" level="WARN" />
+			<AppenderRef ref="FILE_ERROR" level="ERROR" />
+		</Logger>
+
+
+		<root level="TRACE">
+
+		</root>
+
+	</Loggers>
+
+</Configuration>

src/test/java/com/ossez/lang/tutorial/tests/BitOperationTest.java

@@ -0,0 +1,36 @@
+package com.ossez.lang.tutorial.tests;
+
+import org.apache.commons.math3.util.FastMath;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class BitOperationTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(BitOperationTest.class);
+
+	/**
+	 * 35 https://www.lintcode.com/problem/reverse-linked-list/description
+	 */
+	@Test
+	public void testInt2Bit() {
+		logger.debug("BEGIN");
+		System.out.println(Integer.toBinaryString(5));
+		System.out.println(Integer.toBinaryString(2));
+
+		System.out.println(Integer.toBinaryString(2 << 2));
+
+		System.out.println(Integer.parseInt(Integer.toBinaryString(2 << 2), 2));
+
+		System.out.println(5 / 3);
+		System.out.println(5 % 3);
+		FastMath.pow(2, 3);
+
+	}
+
+}

src/test/java/com/ossez/lang/tutorial/tests/DiscourseImportTest.java

@@ -0,0 +1,137 @@
+package com.ossez.lang.tutorial.tests;
+
+import com.google.gson.Gson;
+import com.ossez.edtestbank.common.dao.Factory;
+import com.ossez.edtestbank.common.dao.factories.PostFactory;
+import com.ossez.edtestbank.common.model.entity.BBSOssezForumAttach;
+import com.ossez.edtestbank.common.model.entity.BBSOssezForumPost;
+import com.ossez.edtestbank.common.model.request.TopicRequest;
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.commons.lang3.math.NumberUtils;
+import org.apache.http.HttpHeaders;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpPost;
+import org.apache.http.entity.StringEntity;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClients;
+import org.apache.http.util.EntityUtils;
+import org.joda.time.DateTime;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+/**
+ * Test Logger and function
+ *
+ * @author YuCheng Hu
+ */
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+public class PostTest {
+    private static Logger logger = LoggerFactory.getLogger(PostTest.class);
+
+
+    @BeforeAll
+    protected void setUp() throws Exception {
+        Factory.beginTransaction();
+    }
+
+    @AfterAll
+    protected void tearDown() throws Exception {
+        Factory.rollbackTransaction();
+    }
+
+    /**
+     * Tests search functionality for the customer object.
+     */
+    @Test
+    public void testPost() throws IOException, InterruptedException {
+        List<String> idList = FileUtils.readLines(new File("C:\\Users\\yhu\\Pictures\\Pics\\2021-01\\1.txt"));
+        for (String id : idList) {
+            processPost(NumberUtils.toLong(id));
+            Thread.sleep(6000);
+//            break;
+
+        }
+
+
+        // make sure the customer was found
+//        assertNotNull(bbsOssezForumPost);
+    }
+
+    @Test
+    public void testDateTime() throws IOException {
+        DateTime dateTime = new DateTime(1256834117 * 1000L);
+        System.out.println(dateTime.toString());
+
+    }
+
+    private void processPost(Long tid) throws IOException {
+        BBSOssezForumPost bbsOssezForumPost = PostFactory.getBBSOssezForumPostTid(tid);
+        if (bbsOssezForumPost == null)
+            return;
+
+        logger.debug("Questions Content - {}", bbsOssezForumPost.getSubject());
+
+        String postCtx = bbsOssezForumPost.getMessage();
+//        logger.debug(">>>>{}", postCtx);
+
+
+        String pattern = "\\[attach\\]((\\d)*?)\\[\\/attach\\]";
+
+        // Create a Pattern object
+        Pattern r = Pattern.compile(pattern);
+
+        // Now create matcher object.
+        Matcher m = r.matcher(postCtx);
+
+        while (m.find()) {
+            String attachId = StringUtils.substringBetween(m.group(0), "[attach]", "[/attach]");
+            logger.debug("{}", attachId);
+            BBSOssezForumAttach bbsOssezForumAttach = PostFactory.getBBSOssezForumAttach(NumberUtils.toLong(attachId));
+            if (bbsOssezForumAttach!= null) {
+                String fullURL = "![](https://cdn.ossez.com/com-ossez-www/data/attachment/forum/" + bbsOssezForumAttach.getAttachment() + ")";
+                postCtx = StringUtils.replace(postCtx, m.group(0), fullURL);
+            }
+        }
+
+        logger.debug("{}", postCtx);
+
+
+        CloseableHttpClient client = HttpClients.createDefault();
+
+        HttpPost httpPost = new HttpPost("https://www.ossez.com/posts.json");
+        httpPost.setHeader(HttpHeaders.CONTENT_TYPE, "application/json; charset=UTF-8");
+        httpPost.setHeader("Api-Key", "XXXXXX");
+        httpPost.setHeader("Api-Username", "XXXXXX");
+
+        TopicRequest topicRequest = new TopicRequest();
+        topicRequest.setTitle(bbsOssezForumPost.getSubject());
+        topicRequest.setRaw(postCtx);
+        topicRequest.setCreated_at(new DateTime(bbsOssezForumPost.getDateline() * 1000L).toString() );
+        topicRequest.setCategory(30);
+
+        StringEntity postingString = new StringEntity(new Gson().toJson(topicRequest),  StandardCharsets.UTF_8);
+
+        httpPost.setEntity(postingString);
+
+
+        CloseableHttpResponse response = client.execute(httpPost);
+
+        logger.info("{}", EntityUtils.toString(response.getEntity()), StandardCharsets.UTF_8);
+        client.close();
+    }
+
+}

src/test/java/com/ossez/lang/tutorial/tests/LintcodeTest.java

@@ -0,0 +1,293 @@
+package com.ossez.lang.tutorial.tests;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.TreeSet;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.management.ListenerNotFoundException;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.ossez.lang.tutorial.models.ListNode;
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintcodeTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintcodeTest.class);
+
+	/**
+	 * 35 https://www.lintcode.com/problem/reverse-linked-list/description
+	 */
+	@Test
+	public void test0035Reverse() {
+		// INIT LINKED LIST
+		ListNode head = new ListNode(1);
+		head.next = new ListNode(2);
+		head.next.next = new ListNode(3);
+
+		// CHECK BEFORE
+		System.out.println(head.val);
+		System.out.println(head.next.val);
+		System.out.println(head.next.next.val);
+
+		// REVERSE
+		ListNode prev = null;
+		while (head != null) {
+			ListNode temp = head.next;
+			head.next = prev;
+			prev = head;
+			head = temp;
+		}
+
+		// CHECK AFTER
+		System.out.println(prev.val);
+		System.out.println(prev.next.val);
+		System.out.println(prev.next.next.val);
+	}
+
+	/**
+	 * 1480 https://www.lintcode.com/problem/dot-product/description
+	 */
+	@Test
+	public void test0044minSubArray() {
+
+		List<Integer> nums = new ArrayList<Integer>();
+		nums.add(1);
+		nums.add(1);
+
+		int min_ending_here = 0;
+		int retStatus = 0;
+
+		for (int i = 0; i < nums.size(); i++) {
+			if (min_ending_here > 0) {
+				min_ending_here = nums.get(i);
+			} else {
+				min_ending_here += nums.get(i);
+			}
+			retStatus = Math.min(retStatus, min_ending_here);
+		}
+
+		System.out.println(retStatus);
+
+	}
+
+	/**
+	 * 53 https://www.lintcode.com/problem/reverse-words-in-a-string/description
+	 */
+	@Test
+	public void test0053ReverseWords() {
+
+		String s = "  Life  doesn't  always    give     us  the       joys we want.";
+
+		String retStr = "";
+		String[] inStr = s.split(" ");
+
+		for (int i = inStr.length - 1; i >= 0; i--) {
+			String cStr = inStr[i].trim();
+			if (!cStr.isEmpty()) {
+				retStr = retStr + " " + cStr;
+			}
+		}
+		retStr = retStr.trim();
+		System.out.println(retStr);
+		// return retStr;
+	}
+
+	/**
+	 * 56 https://www.lintcode.com/problem/two-sum/description
+	 */
+	@Test
+	public void test0056TwoSum() {
+		int[] numbers = { 2, 7, 11, 15 };
+		int target = 9;
+
+		int[] retArray = new int[2];
+
+		for (int i = 0; i < numbers.length; i++) {
+			int intA = numbers[i];
+			int intB = 0;
+
+			for (int j = 1 + i; j < numbers.length; j++) {
+				intB = numbers[j];
+				// SUM CHECK
+				if (target == intA + intB && i < j) {
+					retArray[0] = i;
+					retArray[1] = j;
+					break;
+				}
+			}
+		}
+
+		System.out.println(Arrays.toString(retArray));
+	}
+
+	/**
+	 * 209 https://www.lintcode.com/problem/first-unique-character-in-a-string
+	 */
+	@Test
+	public void test0209FirstUniqChar() {
+		String str = "ddjdz";
+
+		char retStatus = 0;
+
+		// LOOP CHECK
+		for (int i = 0; i < 30; i++) {
+			char c = str.charAt(0);
+			if (str.indexOf(Character.toString(c)) == str.lastIndexOf(Character.toString(c))) {
+				retStatus = c;
+				break;
+			}
+			str = str.replaceAll(Character.toString(c), "");
+		}
+
+		System.out.println("" + retStatus);
+	}
+
+	/**
+	 * 411
+	 * 
+	 * <p>
+	 * <ul>
+	 * <li>@see
+	 * <a href="https://www.cwiki.us/display/ITCLASSIFICATION/Gray+Code">https://www.cwiki.us/display/ITCLASSIFICATION/Gray+Code</a>
+	 * <li>@see<a href="https://www.lintcode.com/problem/gray-code/description">https://www.lintcode.com/problem/gray-code/description</a>
+	 * </ul>
+	 * </p>
+	 * 
+	 */
+	@Test
+	public void test0411GrayCode() {
+		int n = 2;
+
+		List<Integer> retArray = new ArrayList<>();
+
+		if (n == 0) {
+			retArray.add(0);
+		}
+
+		for (int i = 0; i < (2 << (n - 1)); i++) {
+			int g = i ^ (i / 2);
+			retArray.add(g);
+		}
+
+		System.out.println(retArray);
+	}
+
+	/**
+	 * 1480 https://www.lintcode.com/problem/dot-product/description
+	 */
+	@Test
+	public void test0423IsValidParentheses() {
+		String s = "([)]";
+
+		boolean retStatus = false;
+		for (int i = 0; i < 3; i++) {
+			s = s.replace("()", "");
+			s = s.replace("{}", "");
+			s = s.replace("[]", "");
+
+			if (s.length() == 0) {
+				retStatus = true;
+				break;
+			}
+		}
+
+		System.out.println(retStatus);
+
+	}
+
+	/**
+	 * 646 https://www.lintcode.com/problem/first-position-unique-character/description
+	 */
+	@Test
+	public void test0646FirstUniqChar() {
+		String s = "saau";
+
+		int retStatus = -1;
+		boolean breakLoop = false;
+
+		int[] iArray = new int[256];
+
+		// NULL CHECK
+		if (s == null || s.length() == 0) {
+			retStatus = -1;
+		}
+
+		// LOOP CHECK
+		for (char c : s.toCharArray()) {
+			iArray[c]++;
+		}
+		for (int i = 0; i < s.length(); i++) {
+			if (iArray[s.charAt(i)] == 1) {
+				retStatus = i;
+				breakLoop = true;
+				break;
+			}
+		}
+
+		// LOOP BREAK CHECK
+		if (!breakLoop) {
+			retStatus = -1;
+		}
+
+		System.out.println(retStatus);
+	}
+
+	/**
+	 * 767 https://www.lintcode.com/problem/reverse-array/description
+	 */
+	@Test
+	public void test0767ReverseArray() {
+		int[] nums = { 1, 2, 3, 4, 5, 6, 7 };
+
+		for (int i = 0; i < nums.length / 2; i++) {
+			int tmp = nums[i];
+			nums[i] = nums[nums.length - 1 - i];
+			nums[nums.length - 1 - i] = tmp;
+		}
+
+		System.out.println(Arrays.toString(nums));
+
+	}
+
+	/**
+	 * 1480 https://www.lintcode.com/problem/dot-product/description
+	 */
+	@Test
+	public void test1377findSubstring() {
+		String str = "";
+		int k = 5;
+
+		HashSet<String> strSet = new HashSet<String>();
+
+		for (int i = 0; i <= str.length() - k; i++) {
+			String subStr = str.substring(i, i + k);
+
+			String pattern = ".*(.).*\\1.*";
+
+			Pattern r = Pattern.compile(pattern);
+
+			Matcher m = r.matcher(subStr);
+			if (!m.find()) {
+				strSet.add(subStr);
+			}
+
+		}
+
+		System.out.println(strSet.size());
+	}
+
+}

src/test/java/com/ossez/lang/tutorial/tests/SingletonTest.java

@@ -0,0 +1,69 @@
+package com.ossez.lang.tutorial.tests;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Eager Singleton
+ * 
+ * @author YuCheng
+ *
+ */
+class EagerSingleton {
+	private static final EagerSingleton INSTANCE = new EagerSingleton();
+
+	// Private constructor suppresses
+	private EagerSingleton() {
+	}
+
+	// default public constructor
+	public static EagerSingleton getInstance() {
+		return INSTANCE;
+	}
+}
+
+/**
+ * Lazy Singleton
+ * 
+ * @author YuCheng
+ *
+ */
+class LazySingleton {
+	private static volatile LazySingleton INSTANCE = null;
+
+	// Private constructor suppresses
+	// default LazySingleton constructor
+	private LazySingleton() {
+	}
+
+	// thread safe and performance promote
+	public static LazySingleton getInstance() {
+		if (INSTANCE == null) {
+			synchronized (LazySingleton.class) {
+				// when more than two threads run into the first null check same time, to avoid instanced more than one time, it needs to be
+				// checked again.
+				if (INSTANCE == null) {
+					INSTANCE = new LazySingleton();
+				}
+			}
+		}
+		return INSTANCE;
+	}
+}
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class SingletonTest {
+	private final static Logger logger = LoggerFactory.getLogger(SingletonTest.class);
+
+	@Test
+	public void testSingleton() {
+		logger.debug("TEST Singleton");
+
+	}
+
+}

src/test/java/com/ossez/lang/tutorial/tests/TreeTest.java

@@ -0,0 +1,85 @@
+package com.ossez.lang.tutorial.tests;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.ossez.lang.tutorial.models.TreeNode;
+import com.ossez.lang.tutorial.utils.TreeUtils;
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class TreeTest {
+	private final static Logger logger = LoggerFactory.getLogger(TreeTest.class);
+	private static List<Integer> loopList = new ArrayList<Integer>();
+
+	@Test
+	public void testMain() {
+		logger.debug("TREE TEST");
+		String data = "{1,2,3,4,5,#,6,#,#,7,8,#,#}";
+		TreeNode treeNode = TreeUtils.initTree(data);
+
+		// PRE
+		loopList = new ArrayList<Integer>();
+		preOrderTraverselRecursion(treeNode);
+		System.out.println(loopList);
+
+		// IN
+		loopList = new ArrayList<Integer>();
+		inOrderTraverselRecursion(treeNode);
+		System.out.println(loopList);
+
+		// POST
+		loopList = new ArrayList<Integer>();
+		postOrderTraversalRecursion(treeNode);
+		System.out.println(loopList);
+	}
+	
+	
+	
+
+	/**
+	 * 
+	 * @param root
+	 */
+	public void preOrderTraverselRecursion(TreeNode root) {
+		if (root != null) {
+			loopList.add(root.val);
+			preOrderTraverselRecursion(root.left);
+			preOrderTraverselRecursion(root.right);
+		}
+	}
+
+	/**
+	 * 
+	 * @param root
+	 */
+	public void inOrderTraverselRecursion(TreeNode root) {
+		if (root != null) {
+			inOrderTraverselRecursion(root.left);
+			loopList.add(root.val);
+			inOrderTraverselRecursion(root.right);
+		}
+
+	}
+
+	/**
+	 * 
+	 * @param root
+	 */
+	public void postOrderTraversalRecursion(TreeNode root) {
+		if (root != null) {
+			postOrderTraversalRecursion(root.left);
+			postOrderTraversalRecursion(root.right);
+			loopList.add(root.val);
+		}
+
+	}
+
+}

src/test/java/com/ossez/lang/tutorial/tests/VariableTest.java

@@ -0,0 +1,49 @@
+package com.ossez.lang.tutorial.tests;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import junit.framework.TestCase;
+
+/**
+ * Object of VariableOssez
+ * 
+ * @author YuCheng
+ *
+ */
+class OssezVariable {
+	int s1, s2;
+	static int s3;
+
+	OssezVariable(int x, int y, int z) {
+		s1 = x;
+		s2 = y;
+		s3 = z;
+	}
+}
+
+/**
+ * 
+ * @author YuCheng
+ *
+ */
+public class VariableTest extends TestCase {
+
+	private final static Logger logger = LoggerFactory.getLogger(VariableTest.class);
+
+	/**
+	 * Do RetsServerConnection Test
+	 */
+	@Test
+	public void testStaticVariableChange() {
+
+		OssezVariable objA = new OssezVariable(1, 2, 3);
+		logger.debug("s1/s2/s3 - [{}]/[{}]/[{}]", objA.s1, objA.s2, OssezVariable.s3);
+
+		OssezVariable objB = new OssezVariable(4, 5, 6);
+		logger.debug("s1/s2/s3 - [{}]/[{}]/[{}]", objA.s1, objA.s2, OssezVariable.s3);
+		logger.debug("s1/s2/s3 - [{}]/[{}]/[{}]", objB.s1, objB.s2, OssezVariable.s3);
+	}
+
+}

src/test/java/com/ossez/lang/tutorial/tests/codility/CodilityBinaryGapTest.java

@@ -0,0 +1,56 @@
+package com.ossez.lang.tutorial.tests.codility;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>
+ * More details about question see link below
+ * <ul>
+ * <li>@see <a href= "https://www.cwiki.us/display/ITCLASSIFICATION/Binary+Gap">https://www.cwiki.us/display/ITCLASSIFICATION/Binary+Gap</a>
+ * </li>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class CodilityBinaryGapTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(CodilityBinaryGapTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("BEGIN");
+
+		int N = 529;
+		String intStr = Integer.toBinaryString(N);
+
+		intStr = intStr.replace("1", "#1#");
+
+		String[] strArray = intStr.split("1");
+
+		int maxCount = 0;
+		for (int i = 0; i < strArray.length; i++) {
+			String checkStr = strArray[i];
+			int countLength = 0;
+
+			if (checkStr.length() > 2 && checkStr.startsWith("#") && checkStr.endsWith("#")) {
+				checkStr = checkStr.replace("#", "");
+				countLength = checkStr.length();
+
+				if (maxCount < countLength) {
+					maxCount = countLength;
+				}
+
+			}
+		}
+
+		logger.debug("MAX COUNT: [{}]", maxCount);
+	}
+
+}

src/test/java/com/ossez/lang/tutorial/tests/lintcode/LintCode0007SerializeAndDeserializeTest.java

@@ -0,0 +1,131 @@
+package com.ossez.lang.tutorial.tests.lintcode;
+
+import java.util.ArrayList;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.ossez.lang.tutorial.models.TreeNode;
+
+/**
+ * <p>
+ * 7
+ * <ul>
+ * <li>@see <a href=
+ * "https://www.cwiki.us/display/ITCLASSIFICATION/Serialize+and+Deserialize+Binary+Tree">https://www.cwiki.us/display/ITCLASSIFICATION/Serialize+and+Deserialize+Binary+Tree</a>
+ * <li>@see<a href=
+ * "https://www.lintcode.com/problem/serialize-and-deserialize-binary-tree">https://www.lintcode.com/problem/serialize-and-deserialize-binary-tree</a>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintCode0007SerializeAndDeserializeTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintCode0007SerializeAndDeserializeTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("BEGIN");
+		String data = "{3,9,20,#,#,15,7}";
+
+		System.out.println(serialize(deserialize(data)));
+
+	}
+
+	/**
+	 * Deserialize from array to tree
+	 * 
+	 * @param data
+	 * @return
+	 */
+	private TreeNode deserialize(String data) {
+		// NULL CHECK
+		if (data.equals("{}")) {
+			return null;
+		}
+
+		ArrayList<TreeNode> treeList = new ArrayList<TreeNode>();
+
+		data = data.replace("{", "");
+		data = data.replace("}", "");
+		String[] vals = data.split(",");
+
+		// INSERT ROOT
+		TreeNode root = new TreeNode(Integer.parseInt(vals[0]));
+		treeList.add(root);
+
+		int index = 0;
+		boolean isLeftChild = true;
+		for (int i = 1; i < vals.length; i++) {
+			if (!vals[i].equals("#")) {
+				TreeNode node = new TreeNode(Integer.parseInt(vals[i]));
+				if (isLeftChild) {
+					treeList.get(index).left = node;
+				} else {
+					treeList.get(index).right = node;
+				}
+				treeList.add(node);
+			}
+
+			// LEVEL
+			if (!isLeftChild) {
+				index++;
+			}
+
+			// MOVE TO RIGHT OR NEXT LEVEL
+			isLeftChild = !isLeftChild;
+		}
+
+		return root;
+
+	}
+
+	/**
+	 * 
+	 * @param root
+	 * @return
+	 */
+	public String serialize(TreeNode root) {
+		// write your code here
+		if (root == null) {
+			return "{}";
+		}
+
+		ArrayList<TreeNode> queue = new ArrayList<TreeNode>();
+		queue.add(root);
+
+		for (int i = 0; i < queue.size(); i++) {
+			TreeNode node = queue.get(i);
+			if (node == null) {
+				continue;
+			}
+			queue.add(node.left);
+			queue.add(node.right);
+		}
+
+		while (queue.get(queue.size() - 1) == null) {
+			queue.remove(queue.size() - 1);
+		}
+
+		StringBuilder sb = new StringBuilder();
+		sb.append("{");
+		sb.append(queue.get(0).val);
+		for (int i = 1; i < queue.size(); i++) {
+			if (queue.get(i) == null) {
+				sb.append(",#");
+			} else {
+				sb.append(",");
+				sb.append(queue.get(i).val);
+			}
+		}
+		sb.append("}");
+		return sb.toString();
+	}
+
+}

src/test/java/com/ossez/lang/tutorial/tests/lintcode/LintCode0069LevelOrderTest.java

@@ -0,0 +1,124 @@
+package com.ossez.lang.tutorial.tests.lintcode;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.ossez.lang.tutorial.models.TreeNode;
+
+/**
+ * <p>
+ * 69
+ * <ul>
+ * <li>@see <a href=
+ * "https://www.cwiki.us/display/ITCLASSIFICATION/Binary+Tree+Level+Order+Traversal">https://www.cwiki.us/display/ITCLASSIFICATION/Binary+Tree+Level+Order+Traversal</a>
+ * <li>@see<a href=
+ * "https://www.lintcode.com/problem/binary-tree-level-order-traversal">https://www.lintcode.com/problem/binary-tree-level-order-traversal</a>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintCode0069LevelOrderTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintCode0069LevelOrderTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("BEGIN");
+		String data = "{3,9,20,#,#,15,7}";
+
+		TreeNode tn = deserialize(data);
+		System.out.println(levelOrder(tn));
+
+	}
+
+	/**
+	 * Deserialize from array to tree
+	 * 
+	 * @param data
+	 * @return
+	 */
+	private TreeNode deserialize(String data) {
+		// NULL CHECK
+		if (data.equals("{}")) {
+			return null;
+		}
+
+		ArrayList<TreeNode> treeList = new ArrayList<TreeNode>();
+
+		data = data.replace("{", "");
+		data = data.replace("}", "");
+		String[] vals = data.split(",");
+
+		// INSERT ROOT
+		TreeNode root = new TreeNode(Integer.parseInt(vals[0]));
+		treeList.add(root);
+
+		int index = 0;
+		boolean isLeftChild = true;
+		for (int i = 1; i < vals.length; i++) {
+			if (!vals[i].equals("#")) {
+				TreeNode node = new TreeNode(Integer.parseInt(vals[i]));
+				if (isLeftChild) {
+					treeList.get(index).left = node;
+				} else {
+					treeList.get(index).right = node;
+				}
+				treeList.add(node);
+			}
+
+			// LEVEL
+			if (!isLeftChild) {
+				index++;
+			}
+
+			// MOVE TO RIGHT OR NEXT LEVEL
+			isLeftChild = !isLeftChild;
+		}
+
+		return root;
+
+	}
+
+	private List<List<Integer>> levelOrder(TreeNode root) {
+		Queue<TreeNode> queue = new LinkedList<TreeNode>();
+		List<List<Integer>> rs = new ArrayList<List<Integer>>();
+
+		// NULL CHECK
+		if (root == null) {
+			return rs;
+		}
+
+		queue.offer(root);
+
+		while (!queue.isEmpty()) {
+			int length = queue.size();
+			List<Integer> list = new ArrayList<Integer>();
+
+			for (int i = 0; i < length; i++) {
+				TreeNode curTN = queue.poll();
+				list.add(curTN.val);
+				if (curTN.left != null) {
+					queue.offer(curTN.left);
+				}
+				if (curTN.right != null) {
+					queue.offer(curTN.right);
+				}
+			}
+
+			rs.add(list);
+		}
+
+		return rs;
+	}
+}

src/test/java/com/ossez/lang/tutorial/tests/lintcode/LintCode0102HasCycleTest.java

@@ -0,0 +1,63 @@
+package com.ossez.lang.tutorial.tests.lintcode;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.ossez.lang.tutorial.models.ListNode;
+
+/**
+ * <p>
+ * 102
+ * <ul>
+ * <li>@see <a href=
+ * "https://www.cwiki.us/display/ITCLASSIFICATION/Linked+List+Cycle">https://www.cwiki.us/display/ITCLASSIFICATION/Linked+List+Cycle</a>
+ * <li>@see<a href= "https://www.lintcode.com/problem/linked-list-cycle/">https://www.lintcode.com/problem/linked-list-cycle/</a>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintCode0102HasCycleTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintCode0102HasCycleTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("BEGIN");
+		// INIT LINKED LIST
+		ListNode head = new ListNode(1);
+		head.next = new ListNode(2);
+		head.next.next = new ListNode(3);
+		head.next.next.next = new ListNode(4);
+
+		// CREATE A LOOP
+		head.next.next.next.next = head.next.next.next;
+
+		boolean retResult = false;
+
+		// LIKED LIST MAY NULL:
+		if (!(head == null || head.next == null)) {
+			ListNode s = head;
+			ListNode f = head.next;
+
+			while (f.next != null && f.next.next != null) {
+
+				s = s.next;
+				f = f.next.next;
+
+				if (f == s) {
+					retResult = true;
+					break;
+				}
+			}
+		}
+
+		System.out.println(retResult);
+
+	}
+}

src/test/java/com/ossez/lang/tutorial/tests/lintcode/LintCode0165MergeTwoListsTest.java

@@ -0,0 +1,89 @@
+package com.ossez.lang.tutorial.tests.lintcode;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.ossez.lang.tutorial.models.ListNode;
+
+/**
+ * <p>
+ * 102
+ * <ul>
+ * <li>@see <a href=
+ * "https://www.cwiki.us/display/ITCLASSIFICATION/Linked+List+Cycle">https://www.cwiki.us/display/ITCLASSIFICATION/Linked+List+Cycle</a>
+ * <li>@see<a href= "https://www.lintcode.com/problem/linked-list-cycle/">https://www.lintcode.com/problem/linked-list-cycle/</a>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintCode0165MergeTwoListsTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintCode0165MergeTwoListsTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("BEGIN");
+		// INIT LINKED LIST l1
+		ListNode l1 = new ListNode(1);
+		l1.next = new ListNode(3);
+		l1.next.next = new ListNode(8);
+		l1.next.next.next = new ListNode(11);
+		l1.next.next.next.next = new ListNode(15);
+
+		// INIT LINKED LIST l2
+		ListNode l2 = new ListNode(2);
+
+		// RETURN RESULT
+		ListNode retResult = new ListNode(0);
+
+		// NULL CHECK
+		// if (l1 == null && l2 == null) {
+		// retResult = null;
+		// }
+		//
+		// if (l1 == null) {
+		// retResult = l2;
+		// }
+		//
+		// if (l2 == null) {
+		// retResult = l1;
+		// }
+
+		// MERGE
+		retResult = new ListNode(0);
+		ListNode tmpNode = new ListNode(0);
+		retResult = tmpNode;
+		while (l1 != null & l2 != null) {
+			if (l1.val <= l2.val) {
+				tmpNode.next = l1;
+				l1 = l1.next;
+			} else {
+				tmpNode.next = l2;
+				l2 = l2.next;
+			}
+
+			tmpNode = tmpNode.next;
+		}
+
+		if (l1 == null) {
+			tmpNode.next = l2;
+		}
+
+		if (l2 == null) {
+			tmpNode.next = l1;
+		}
+
+		retResult = retResult.next;
+
+		System.out.println(retResult.val);
+		System.out.println(retResult.next.val);
+		System.out.println(retResult.next.next.val);
+
+	}
+}

src/test/java/com/ossez/lang/tutorial/tests/lintcode/LintCode0425LetterCombinationsTest.java

@@ -0,0 +1,78 @@
+package com.ossez.lang.tutorial.tests.lintcode;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>
+ * 425
+ * <ul>
+ * <li>@see <a href=
+ * "https://www.cwiki.us/display/ITCLASSIFICATION/Letter+Combinations+of+a+Phone+Number">https://www.cwiki.us/display/ITCLASSIFICATION/Letter+Combinations+of+a+Phone+Number</a>
+ * <li>@see<a href=
+ * "https://www.lintcode.com/problem/letter-combinations-of-a-phone-number/description">https://www.lintcode.com/problem/letter-combinations-of-a-phone-number/description</a>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintCode0425LetterCombinationsTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintCode0425LetterCombinationsTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("LetterCombinationsTest");
+		String digits = "23";
+
+		HashMap<String, String> phoneKeyMap = new HashMap<String, String>();
+		phoneKeyMap.put("0", "");
+		phoneKeyMap.put("1", "");
+		phoneKeyMap.put("2", "abc");
+		phoneKeyMap.put("3", "def");
+		phoneKeyMap.put("4", "ghi");
+		phoneKeyMap.put("5", "jkl");
+		phoneKeyMap.put("6", "mno");
+		phoneKeyMap.put("7", "pqrs");
+		phoneKeyMap.put("8", "tuv");
+		phoneKeyMap.put("9", "wxyz");
+
+		List<String> retStatus = new ArrayList<>();
+
+		if (digits != null && digits.length() != 0) {
+			phoneRecursive(digits, retStatus, phoneKeyMap, "", 0);
+		}
+
+		System.out.println(retStatus);
+	}
+
+	/**
+	 * phoneRecursive
+	 * 
+	 * @param digits
+	 * @param retStatus
+	 * @param phoneKeyMap
+	 * @param comb
+	 * @param index
+	 */
+	private void phoneRecursive(String digits, List<String> retStatus, HashMap<String, String> phoneKeyMap, String comb, int index) {
+		if (index == digits.length()) {
+			retStatus.add(comb);
+			return;
+		}
+
+		char pos = digits.charAt(index);
+		for (char c : ((String) phoneKeyMap.get(String.valueOf(pos))).toCharArray()) {
+			phoneRecursive(digits, retStatus, phoneKeyMap, comb + c, index + 1);
+		}
+	}
+}

src/test/java/com/ossez/lang/tutorial/tests/lintcode/LintCode0433NumIslandsTest.java

@@ -0,0 +1,94 @@
+package com.ossez.lang.tutorial.tests.lintcode;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>
+ * 433
+ * <ul>
+ * <li>@see <a href=
+ * "https://www.cwiki.us/display/ITCLASSIFICATION/Number+of+Islands">https://www.cwiki.us/display/ITCLASSIFICATION/Number+of+Islands</a>
+ * <li>@see<a href="https://www.lintcode.com/problem/number-of-islands/">https://www.lintcode.com/problem/number-of-islands/</a>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintCode0433NumIslandsTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintCode0433NumIslandsTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("BEGIN");
+		// INIT GRID
+		boolean[][] grid = { { true, true, false, false, false }, { false, true, false, false, true }, { false, false, false, true, true },
+				{ false, false, false, false, false }, { false, false, false, false, true }
+
+		};
+
+		// NULL CHECK
+		if (grid.length == 0 || grid[0].length == 0) {
+			System.out.println("NULL");
+			// return 0;
+		}
+
+		// GET SIZE
+		int n = grid.length;
+		int m = grid[0].length;
+
+		// ARRAY FOR VISITED LOG
+		boolean[][] visited = new boolean[n][m];
+
+		int count = 0;
+
+		// LOOP FOR GRID
+		for (int i = 0; i < n; i++) {
+			for (int j = 0; j < m; j++) {
+				if (grid[i][j] && !visited[i][j]) {
+					numIslandsDFS(grid, visited, i, j);
+					count++;
+				}
+			}
+		}
+
+		System.out.println(count);
+
+	}
+
+	/**
+	 * 
+	 * @param grid
+	 * @param visited
+	 * @param x
+	 * @param y
+	 */
+	public void numIslandsDFS(boolean[][] grid, boolean[][] visited, int x, int y) {
+		if (x < 0 || x >= grid.length) {
+			return;
+		}
+
+		if (y < 0 || y >= grid[0].length) {
+			return;
+		}
+
+		if (grid[x][y] != true || visited[x][y]) {
+			return;
+		}
+
+		visited[x][y] = true;
+
+		// Recursive call
+		numIslandsDFS(grid, visited, x - 1, y);
+		numIslandsDFS(grid, visited, x + 1, y);
+		numIslandsDFS(grid, visited, x, y - 1);
+		numIslandsDFS(grid, visited, x, y + 1);
+
+	}
+}

src/test/java/com/ossez/lang/tutorial/tests/lintcode/LintCode1480DotProductTest.java

@@ -0,0 +1,35 @@
+package com.ossez.lang.tutorial.tests.lintcode;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * <p>
+ * 1480
+ * <ul>
+ * <li>@see
+ * <a href= "https://www.cwiki.us/display/ITCLASSIFICATION/Dot+Product">https://www.cwiki.us/display/ITCLASSIFICATION/Dot+Product</a>
+ * <li>@see<a href= "https://www.lintcode.com/problem/dot-product/">https://www.lintcode.com/problem/dot-product/</a>
+ * </ul>
+ * </p>
+ * 
+ * @author YuCheng
+ *
+ */
+public class LintCode1480DotProductTest {
+
+	private final static Logger logger = LoggerFactory.getLogger(LintCode1480DotProductTest.class);
+
+	/**
+	 * 
+	 */
+	@Test
+	public void testMain() {
+		logger.debug("BEGIN");
+		int t = 87;
+		int[] dur = { 20, 25, 19, 37 };
+		// Write your code here
+	}
+
+}

src/test/resources/log4j2.xml

@@ -0,0 +1,97 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE RelativeLayout>
+<Configuration status="WARN">
+
+	<Properties>
+		<Property name="baseDir">/home/logs/reoc/services/</Property>
+	</Properties>
+
+	<Appenders>
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- C O N S O L E - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<Console name="CONSOLE" target="SYSTEM_OUT">
+			<PatternLayout pattern="%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n" />
+			<ThresholdFilter level="TRACE" onMatch="ACCEPT" onMismatch="DENY" />
+		</Console>
+
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- D E B U G _ F I L E - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_DEBUG" append="true" fileName="${baseDir}/services_debug.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-debug-%d{yyyy-MM-dd}-%i.log.gz">
+			<ThresholdFilter level="DEBUG" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- I N F O _ F I L E - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_INFO" append="true" fileName="${baseDir}/services_info.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-info-%d{yyyy-MM-dd}.log.gz">
+			<ThresholdFilter level="INFO" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+		
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- F I L E _ W A R N - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_WARN" append="true" fileName="${baseDir}/services_info.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-warn-%d{yyyy-MM-dd}.log.gz">
+			<ThresholdFilter level="WARN" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+		
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<!-- F I L E _ E R R O R - A P P E N D E R -->
+		<!-- ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
+		<RollingFile name="FILE_ERROR" append="true" fileName="${baseDir}/services_error.log" filePattern="${baseDir}/$${date:yyyy-MM}/services-error-%d{yyyy-MM-dd}.log.gz">
+			<ThresholdFilter level="ERROR" onMatch="ACCEPT" onMismatch="DENY" />
+			<PatternLayout>
+				<pattern>%-d{yyyy/MM/dd HH:mm:ss} %-5p [%c] - %m%n</pattern>
+			</PatternLayout>
+			<Policies>
+				<TimeBasedTriggeringPolicy />
+				<SizeBasedTriggeringPolicy size="250 MB"></SizeBasedTriggeringPolicy>
+			</Policies>
+			<DefaultRolloverStrategy max="12" />
+		</RollingFile>
+	</Appenders>
+
+	<!-- LOGGERS -->
+	<Loggers>
+
+		<Logger name="com.ossez" level="TRACE" additivity="false">
+			<AppenderRef ref="CONSOLE" level="DEBUG" />
+			<AppenderRef ref="FILE_DEBUG" level="DEBUG" />
+			<AppenderRef ref="FILE_INFO" level="INFO" />
+			<AppenderRef ref="FILE_WARN" level="WARN" />
+			<AppenderRef ref="FILE_ERROR" level="ERROR" />
+		</Logger>
+
+
+		<root level="TRACE">
+
+		</root>
+
+	</Loggers>
+
+</Configuration>