Merge branch 'eugenp:master' into master

2024-04-13 07:13:04 +02:00
parent 11084b012d 38bb8c3e91
commit 0dffde16a4
833 changed files with 12280 additions and 3250 deletions
@@ -5,6 +5,18 @@
    <modelVersion>4.0.0</modelVersion>
    <artifactId>algorithms-miscellaneous-5</artifactId>
    <version>0.0.1-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>17</source>
+                    <target>17</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
    <name>algorithms-miscellaneous-5</name>

    <parent>
@@ -1,15 +1,12 @@
 package com.baeldung.algorithms.conversion;

-import java.math.BigInteger;
-
-
-
+import com.google.common.io.BaseEncoding;
+import jakarta.xml.bind.DatatypeConverter;
 import org.apache.commons.codec.DecoderException;
 import org.apache.commons.codec.binary.Hex;

-import com.google.common.io.BaseEncoding;
-
-import jakarta.xml.bind.DatatypeConverter;
+import java.math.BigInteger;
+import java.util.HexFormat;

 public class HexStringConverter {

@@ -109,4 +106,14 @@ public class HexStringConverter {
        return BaseEncoding.base16()
            .decode(hexString.toUpperCase());
    }
+
+    public String encodeUsingHexFormat(byte[] bytes) {
+        HexFormat hexFormat = HexFormat.of();
+        return hexFormat.formatHex(bytes);
+    }
+
+    public byte[] decodeUsingHexFormat(String hexString) {
+        HexFormat hexFormat = HexFormat.of();
+        return hexFormat.parseHex(hexString);
+    }
 }
@@ -1,15 +1,13 @@
 package com.baeldung.algorithms.conversion;

-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.junit.jupiter.api.Assertions.assertArrayEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-
 import org.apache.commons.codec.DecoderException;
 import org.hamcrest.text.IsEqualIgnoringCase;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;

-import com.baeldung.algorithms.conversion.HexStringConverter;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;

 class ByteArrayConverterUnitTest {

@@ -24,7 +22,7 @@ class ByteArrayConverterUnitTest {
    void shouldEncodeByteArrayToHexStringUsingBigIntegerToString() {
        byte[] bytes = getSampleBytes();
        String hexString = getSampleHexString();
-        if(hexString.charAt(0) == '0') {
+        if (hexString.charAt(0) == '0') {
            hexString = hexString.substring(1);
        }
        String output = hexStringConverter.encodeUsingBigIntegerToString(bytes);
@@ -46,7 +44,7 @@ class ByteArrayConverterUnitTest {
        byte[] output = hexStringConverter.decodeUsingBigInteger(hexString);
        assertArrayEquals(bytes, output);
    }
-    
+
    @Test
    void shouldEncodeByteArrayToHexStringUsingCharacterConversion() {
        byte[] bytes = getSampleBytes();
@@ -62,7 +60,7 @@ class ByteArrayConverterUnitTest {
        byte[] output = hexStringConverter.decodeHexString(hexString);
        assertArrayEquals(bytes, output);
    }
-    
+
    @Test
    void shouldDecodeHexToByteWithInvalidHexCharacter() {
        assertThrows(IllegalArgumentException.class, () -> {
@@ -118,12 +116,28 @@ class ByteArrayConverterUnitTest {
        assertArrayEquals(bytes, output);
    }

+    @Test
+    void shouldEncodeByteArrayToHexStringUsingHexFormat() throws DecoderException {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        String output = hexStringConverter.encodeUsingHexFormat(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    void shouldDecodeHexStringToByteArrayUsingHexFormat() throws DecoderException {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        byte[] output = hexStringConverter.decodeUsingHexFormat(hexString);
+        assertArrayEquals(bytes, output);
+    }
+
    private String getSampleHexString() {
        return "0af50c0e2d10";
    }

    private byte[] getSampleBytes() {
-        return new byte[] { 10, -11, 12, 14, 45, 16 };
+        return new byte[]{10, -11, 12, 14, 45, 16};
    }

 }
@@ -10,8 +10,4 @@
 - [Check if Two Strings Are Rotations of Each Other](https://www.baeldung.com/java-string-check-strings-rotations)
 - [Find the Largest Prime Under the Given Number in Java](https://www.baeldung.com/java-largest-prime-lower-threshold)
 - [Count the Number of Unique Digits in an Integer using Java](https://www.baeldung.com/java-int-count-unique-digits)
- [Generate Juggler Sequence in Java](https://www.baeldung.com/java-generate-juggler-sequence)
- [Finding the Parent of a Node in a Binary Search Tree with Java](https://www.baeldung.com/java-find-parent-node-binary-search-tree)
- [Check if a Number Is a Happy Number in Java](https://www.baeldung.com/java-happy-sad-number-test)
- [Find the Largest Number Possible After Removing k Digits of a Number](https://www.baeldung.com/java-find-largest-number-remove-k-digits)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-6)
@@ -13,4 +13,22 @@
        <version>1.0.0-SNAPSHOT</version>
    </parent>

+    <properties>
+        <jmh.version>1.35</jmh.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh.version}</version>
+        </dependency>
+    </dependencies>
+
 </project>
@@ -0,0 +1,50 @@
+package com.baeldung.algorithms.perfectnumber;
+
+import java.util.stream.IntStream;
+
+class PerfectNumber {
+
+    public static boolean isPerfectBruteForce(int number) {
+        int sum = 0;
+        for (int i = 1; i <= number / 2; i++) {
+            if (number % i == 0) {
+                sum += i;
+            }
+        }
+        return sum == number;
+    }
+
+    public static boolean isPerfectStream(int number) {
+        int sum = IntStream.rangeClosed(2, (int) Math.sqrt(number))
+                .filter(test -> number % test == 0)
+                .reduce(1, (s, test) -> s + test + (number / test));
+        return sum == number;
+    }
+
+    public static boolean isPerfectEuclidEuler(int number) {
+        int p = 2;
+        int perfectNumber = (int) (Math.pow(2, p - 1) * (Math.pow(2, p) - 1));
+        while (perfectNumber <= number) {
+            if (perfectNumber == number) {
+                return true;
+            }
+            p++;
+            perfectNumber = (int) (Math.pow(2, p - 1) * (Math.pow(2, p) - 1));
+        }
+        return false;
+    }
+
+    public static boolean isPerfectEuclidEulerUsingShift(int number) {
+        int p = 2;
+        int perfectNumber = (2 << (p - 1)) * ((2 << p) - 1);
+        while (perfectNumber <= number) {
+            if (perfectNumber == number) {
+                return true;
+            }
+            p++;
+            perfectNumber = (2 << (p - 1)) * ((2 << p) - 1);
+        }
+        return false;
+    }
+
+}
@@ -0,0 +1,41 @@
+package com.baeldung.algorithms.perfectnumber;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+@State(Scope.Benchmark)
+public class PerfectNumberBenchmark {
+
+    @Benchmark
+    public boolean bruteForceBenchmark() {
+        return PerfectNumber.isPerfectBruteForce(33550336);
+    }
+
+    @Benchmark
+    public boolean streamBenchmark() {
+        return PerfectNumber.isPerfectStream(33550336);
+    }
+
+    @Benchmark
+    public boolean euclidEulerBenchmark() {
+        return PerfectNumber.isPerfectEuclidEuler(33550336);
+    }
+
+    @Benchmark
+    public boolean euclidEulerUsingShiftBenchmark() {
+        return PerfectNumber.isPerfectEuclidEulerUsingShift(33550336);
+    }
+
+    public static void main(String[] args) throws Exception {
+        Options options = new OptionsBuilder()
+                .include(PerfectNumberBenchmark.class.getSimpleName())
+                .forks(1)
+                .build();
+
+        new Runner(options).run();
+    }
+}
@@ -1,2 +0,0 @@
-## Relevant Articles
- [Implement Connect 4 Game with Java](https://www.baeldung.com/java-connect-4-game)
@@ -0,0 +1,68 @@
+package com.baeldung.algorithms.perfectnumber;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class PerfectNumberUnitTest {
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectBruteForce_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectBruteForce(6));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectBruteForce_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectBruteForce(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectBruteForce_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectBruteForce(-28));
+    }
+
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectStream_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectStream(28));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectStream_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectStream(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectStream_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectStream(-6));
+    }
+
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectEuclidEuler_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectEuclidEuler(28));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectEuclidEuler_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEuler(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectEuclidEuler_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEuler(-6));
+    }
+
+    @Test
+    void givenPerfectNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnTrue() {
+        assertTrue(PerfectNumber.isPerfectEuclidEulerUsingShift(28));
+    }
+
+    @Test
+    void givenNonPerfectNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEulerUsingShift(10));
+    }
+
+    @Test
+    void givenNegativeNumber_whenCheckingIsPerfectEuclidEulerUsingShift_thenReturnFalse() {
+        assertFalse(PerfectNumber.isPerfectEuclidEulerUsingShift(-6));
+    }
+}
@@ -0,0 +1,9 @@
+### Relevant Articles: 
+- [Vigenère Cipher in Java](https://www.baeldung.com/java-vigenere-cipher)
+- [Merge Overlapping Intervals in a Java Collection](https://www.baeldung.com/java-collection-merge-overlapping-intervals)
+- [Generate Juggler Sequence in Java](https://www.baeldung.com/java-generate-juggler-sequence)
+- [Finding the Parent of a Node in a Binary Search Tree with Java](https://www.baeldung.com/java-find-parent-node-binary-search-tree)
+- [Check if a Number Is a Happy Number in Java](https://www.baeldung.com/java-happy-sad-number-test)
+- [Find the Largest Number Possible After Removing k Digits of a Number](https://www.baeldung.com/java-find-largest-number-remove-k-digits)
+- [Implement Connect 4 Game with Java](https://www.baeldung.com/java-connect-4-game)
+- More articles: [[<-- prev]](/algorithms-miscellaneous-7)
@@ -1,6 +1,6 @@
 package com.baeldung.algorithms.largestNumberRemovingK;

-import java.util.*;
+import java.util.Stack;

 public class LargestNumberRemoveKDigits {
    public static int findLargestNumberUsingArithmetic(int num, int k) {
@@ -0,0 +1,37 @@
+package com.baeldung.algorithms.mergeintervals;
+
+import java.util.Objects;
+
+public class Interval {
+    int start;
+    int end;
+
+    Interval(int start, int end) {
+        this.start = start;
+        this.end = end;
+    }
+
+    public void setEnd(int end) {
+        this.end = end;
+    }
+
+    @Override
+    public String toString() {
+        return "Interval{" + "start=" + start + ", end=" + end + '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        Interval interval = (Interval) o;
+        return start == interval.start && end == interval.end;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(start, end);
+    }
+}
@@ -0,0 +1,29 @@
+package com.baeldung.algorithms.mergeintervals;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class MergeOverlappingIntervals {
+
+    public List<Interval> doMerge(List<Interval> intervals) {
+        // Sort the intervals based on start time
+        intervals.sort((one, two) -> one.start - two.start);
+
+        // Create somewhere to put the merged list, start it off with the earliest starting interval
+        ArrayList<Interval> merged = new ArrayList<>();
+        merged.add(intervals.get(0));
+
+        // Loop over each interval and merge if start time is before the end time of the
+        // previous interval
+        intervals.forEach(interval -> {
+            if (merged.get(merged.size() - 1).end > interval.start) {
+                merged.get(merged.size() - 1).setEnd(interval.end);
+            } else {
+                merged.add(interval);
+            }
+        });
+
+        return merged;
+    }
+
+}
@@ -0,0 +1,11 @@
+package com.baeldung.algorithms.skiplist;
+
+class Node {
+    int value;
+    Node[] forward; // array to hold references to different levels
+
+    public Node(int value, int level) {
+        this.value = value;
+        this.forward = new Node[level + 1]; // level + 1 because level is 0-based
+    }
+}
@@ -0,0 +1,92 @@
+package com.baeldung.algorithms.skiplist;
+
+
+import java.util.Random;
+
+public class SkipList {
+    private Node head;
+    private int maxLevel;
+    private int level;
+    private Random random;
+
+    public SkipList() {
+        maxLevel = 16; // maximum number of levels
+        level = 0; // current level of SkipList
+        head = new Node(Integer.MIN_VALUE, maxLevel);
+        random = new Random();
+    }
+
+    public void insert(int value) {
+        Node[] update = new Node[maxLevel + 1];
+        Node current = this.head;
+
+        for (int i = level; i >= 0; i--) {
+            while (current.forward[i] != null && current.forward[i].value < value) {
+                current = current.forward[i];
+            }
+            update[i] = current;
+        }
+
+        current = current.forward[0];
+
+        if (current == null || current.value != value) {
+            int lvl = randomLevel();
+
+            if (lvl > level) {
+                for (int i = level + 1; i <= lvl; i++) {
+                    update[i] = head;
+                }
+                level = lvl;
+            }
+
+            Node newNode = new Node(value, lvl);
+            for (int i = 0; i <= lvl; i++) {
+                newNode.forward[i] = update[i].forward[i];
+                update[i].forward[i] = newNode;
+            }
+        }
+    }
+
+    public boolean search(int value) {
+        Node current = this.head;
+        for (int i = level; i >= 0; i--) {
+            while (current.forward[i] != null && current.forward[i].value < value) {
+                current = current.forward[i];
+            }
+        }
+        current = current.forward[0];
+        return current != null && current.value == value;
+    }
+
+    public void delete(int value) {
+        Node[] update = new Node[maxLevel + 1];
+        Node current = this.head;
+
+        for (int i = level; i >= 0; i--) {
+            while (current.forward[i] != null && current.forward[i].value < value) {
+                current = current.forward[i];
+            }
+            update[i] = current;
+        }
+        current = current.forward[0];
+
+        if (current != null && current.value == value) {
+            for (int i = 0; i <= level; i++) {
+                if (update[i].forward[i] != current) break;
+                update[i].forward[i] = current.forward[i];
+            }
+
+            while (level > 0 && head.forward[level] == null) {
+                level--;
+            }
+        }
+    }
+
+    private int randomLevel() {
+        int lvl = 0;
+        while (lvl < maxLevel && random.nextDouble() < 0.5) {
+            lvl++;
+        }
+        return lvl;
+    }
+}
@@ -0,0 +1,82 @@
+package com.baeldung.algorithms.happynumber;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+class HappyNumberDecider {
+
+    public static boolean isHappyNumber(int n) {
+        Set<Integer> checkedNumbers = new HashSet<>();
+        while (true) {
+            n = sumDigitsSquare(n);
+            if (n == 1) {
+                return true;
+            }
+            if (checkedNumbers.contains(n)) {
+                return false;
+            }
+            checkedNumbers.add(n);
+        }
+    }
+
+    public static boolean isHappyNumberFloyd(int n) {
+        int slow = n;
+        int fast = n;
+        do {
+            slow = sumDigitsSquare(slow);
+            fast = sumDigitsSquare(sumDigitsSquare(fast));
+        } while (slow != fast);
+
+        return slow == 1;
+    }
+
+    private static int sumDigitsSquare(int n) {
+        int squareSum = 0;
+        while (n != 0) {
+            squareSum += (n % 10) * (n % 10);
+            n /= 10;
+        }
+        return squareSum;
+    }
+}
+
+public class HappyNumberUnitTest {
+
+    @Test
+    void whenUsingIsHappyNumber_thenGetTheExpectedResult() {
+        assertTrue(HappyNumberDecider.isHappyNumber(7));
+        assertTrue(HappyNumberDecider.isHappyNumber(10));
+        assertTrue(HappyNumberDecider.isHappyNumber(13));
+        assertTrue(HappyNumberDecider.isHappyNumber(19));
+        assertTrue(HappyNumberDecider.isHappyNumber(23));
+
+        assertFalse(HappyNumberDecider.isHappyNumber(4));
+        assertFalse(HappyNumberDecider.isHappyNumber(6));
+        assertFalse(HappyNumberDecider.isHappyNumber(11));
+        assertFalse(HappyNumberDecider.isHappyNumber(15));
+        assertFalse(HappyNumberDecider.isHappyNumber(20));
+
+    }
+
+    @Test
+    void whenUsingIsHappyNumber2_thenGetTheExpectedResult() {
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(7));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(10));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(13));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(19));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(23));
+
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(4));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(6));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(11));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(15));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(20));
+
+    }
+
+}
@@ -0,0 +1,30 @@
+package com.baeldung.algorithms.mergeintervals;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import org.junit.jupiter.api.Test;
+
+class MergeIntervalsUnitTest {
+
+    private ArrayList<Interval> intervals = new ArrayList<>(Arrays.asList(
+      new Interval(2, 5),
+      new Interval(13, 20),
+      new Interval(11, 15),
+      new Interval(1, 3)
+    ));
+    private ArrayList<Interval> intervalsMerged = new ArrayList<>(Arrays.asList(
+      new Interval(1, 5),
+      new Interval(11, 20)
+    ));
+
+    @Test
+    void givenIntervals_whenMerging_thenReturnMergedIntervals() {
+        MergeOverlappingIntervals merger = new MergeOverlappingIntervals();
+        ArrayList<Interval> result = (ArrayList<Interval>) merger.doMerge(intervals);
+        assertArrayEquals(intervalsMerged.toArray(), result.toArray());
+    }
+
+}
@@ -5,7 +5,9 @@ import org.junit.jupiter.api.Test;

 import java.util.NoSuchElementException;

-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertNull;

 class BinaryTreeParentNodeFinderUnitTest {

@@ -0,0 +1,34 @@
+package com.baeldung.algorithms.skiplist;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SkipListUnitTest {
+
+    @Test
+    public void givenSkipList_WhenInsert_ThenSearchFound() {
+        SkipList skipList = new SkipList();
+
+        skipList.insert(3);
+        assertTrue(skipList.search(3), "Should find 3");
+
+        assertFalse(skipList.search(99), "Should not find 99");
+    }
+
+    @Test
+    public void givenSkipList_WhenDeleteElement_ThenRemoveFromList() {
+        SkipList skipList = new SkipList();
+
+        skipList.insert(3);
+        skipList.insert(7);
+
+        skipList.delete(3);
+        assertFalse(skipList.search(3), "3 should have been deleted");
+
+        skipList.delete(99);
+        assertTrue(skipList.search(7), "7 should still exist");
+    }
+
+}
@@ -1,5 +1,6 @@
 ## Relevant Articles
 - [Understanding XSLT Processing in Java](https://www.baeldung.com/java-extensible-stylesheet-language-transformations)
 - [Add Camel Route at Runtime in Java](https://www.baeldung.com/java-camel-dynamic-route)
-
+- [Logging in Apache Camel](https://www.baeldung.com/java-apache-camel-logging)
 - More articles: [[<-- prev]](../apache-libraries)
+
@@ -0,0 +1 @@
+Welcome to Baeldung
@@ -0,0 +1,4 @@
+{
+  "name" : "phillip",
+  "age" : 5
+}
--- a/Show More
+++ b/Show More