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BAEL-1773 Find the middle element of a Linked List. (#4425)

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* BAEL-1773 - find middle element of linked list

* changes from review

* changes from review

* find middle element in linked list

* typo
This commit is contained in:
Marcos Lopez Gonzalez
2018-06-08 07:35:46 +02:00
committed by Predrag Maric
parent 8080f07c6c
commit 0a3d212a2a
3 changed files with 83 additions and 31 deletions
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core-java/src/test/java/com/baeldung/linkedlist/MiddleElementLookupUnitTest.java
+35 -27
View File
@@ -2,51 +2,46 @@ package com.baeldung.linkedlist;
import static org.junit.Assert.assertEquals;
import java.util.LinkedList;
import org.junit.Test;
public class MiddleElementLookupUnitTest {
@Test
public void whenFindingMiddle_thenMiddleFound() {
String middle = MiddleElementLookup.findMiddleElement(createList(5).head());
assertEquals("3", middle);
middle = MiddleElementLookup.findMiddleElement(createList(4).head());
assertEquals("2", middle);
public void whenFindingMiddleLinkedList_thenMiddleFound() {
assertEquals("3", MiddleElementLookup.findMiddleElementLinkedList(createLinkedList(5)));
assertEquals("2", MiddleElementLookup.findMiddleElementLinkedList(createLinkedList(4)));
}
@Test
public void whenFindingMiddle1PassRecursively_thenMiddleFound() {
String middle = MiddleElementLookup.findMiddleElement1PassRecursively(createList(5).head());
assertEquals("3", middle);
middle = MiddleElementLookup.findMiddleElement1PassRecursively(createList(4).head());
assertEquals("2", middle);
public void whenFindingMiddleFromHead_thenMiddleFound() {
assertEquals("3", MiddleElementLookup.findMiddleElementFromHead(createNodesList(5)));
assertEquals("2", MiddleElementLookup.findMiddleElementFromHead(createNodesList(4)));
}
@Test
public void whenFindingMiddle1PassIteratively_thenMiddleFound() {
String middle = MiddleElementLookup.findMiddleElement1PassIteratively(createList(5).head());
assertEquals("3", middle);
public void whenFindingMiddleFromHead1PassRecursively_thenMiddleFound() {
assertEquals("3", MiddleElementLookup.findMiddleElementFromHead1PassRecursively(createNodesList(5)));
assertEquals("2", MiddleElementLookup.findMiddleElementFromHead1PassRecursively(createNodesList(4)));
}
middle = MiddleElementLookup.findMiddleElement1PassIteratively(createList(4).head());
assertEquals("2", middle);
@Test
public void whenFindingMiddleFromHead1PassIteratively_thenMiddleFound() {
assertEquals("3", MiddleElementLookup.findMiddleElementFromHead1PassIteratively(createNodesList(5)));
assertEquals("2", MiddleElementLookup.findMiddleElementFromHead1PassIteratively(createNodesList(4)));
}
@Test
public void whenListEmptyOrNull_thenMiddleNull() {
String middle = MiddleElementLookup.findMiddleElement(null);
assertEquals(null, middle);
middle = MiddleElementLookup.findMiddleElement1PassIteratively(null);
assertEquals(null, middle);
middle = MiddleElementLookup.findMiddleElement1PassRecursively(null);
assertEquals(null, middle);
assertEquals(null, MiddleElementLookup.findMiddleElementLinkedList(null));
assertEquals(null, MiddleElementLookup.findMiddleElementFromHead(null));
assertEquals(null, MiddleElementLookup.findMiddleElementFromHead1PassIteratively(null));
assertEquals(null, MiddleElementLookup.findMiddleElementFromHead1PassRecursively(null));
}
private static LinkedList createList(int n) {
LinkedList list = new LinkedList();
private static LinkedList<String> createLinkedList(int n) {
LinkedList<String> list = new LinkedList<>();
for (int i = 1; i <= n; i++) {
list.add(String.valueOf(i));
@@ -55,4 +50,17 @@ public class MiddleElementLookupUnitTest {
return list;
}
private static Node createNodesList(int n) {
Node head = new Node("1");
Node current = head;
for (int i = 2; i <= n; i++) {
Node newNode = new Node(String.valueOf(i));
current.setNext(newNode);
current = newNode;
}
return head;
}
}