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Merge pull request #10522 from sk1418/Circular_linked_list

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fix the deleting method
This commit is contained in:
Eric Martin 2021-03-03 21:37:39 -06:00 committed by GitHub
commit 1c32920b76
2 changed files with 52 additions and 21 deletions
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29
data-structures/src/main/java/com/baeldung/circularlinkedlist/CircularLinkedList.java
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@ -5,7 +5,7 @@ import org.slf4j.LoggerFactory;
public class CircularLinkedList { public class CircularLinkedList {
final Logger LOGGER = LoggerFactory.getLogger(CircularLinkedList.class); final Logger logger = LoggerFactory.getLogger(CircularLinkedList.class);
private Node head = null; private Node head = null;
private Node tail = null; private Node tail = null;
@ -42,25 +42,30 @@ public class CircularLinkedList {
} }
public void deleteNode(int valueToDelete) { public void deleteNode(int valueToDelete) {
Node currentNode = head; Node currentNode = head;
if (head == null) {
if (head != null) { return;
if (currentNode.value == valueToDelete) { }
head = head.nextNode;
tail.nextNode = head;
} else {
do { do {
Node nextNode = currentNode.nextNode; Node nextNode = currentNode.nextNode;
if (nextNode.value == valueToDelete) { if (nextNode.value == valueToDelete) {
if (tail == head) {
head = null;
tail = null;
} else {
currentNode.nextNode = nextNode.nextNode; currentNode.nextNode = nextNode.nextNode;
if (head == nextNode) {
head = head.nextNode;
}
if (tail == nextNode) {
tail = currentNode;
}
}
break; break;
} }
currentNode = currentNode.nextNode; currentNode = nextNode;
} while (currentNode != head); } while (currentNode != head);
} }
}
}
public void traverseList() { public void traverseList() {
@ -68,7 +73,7 @@ public class CircularLinkedList {
if (head != null) { if (head != null) {
do { do {
LOGGER.info(currentNode.value + " "); logger.info(currentNode.value + " ");
currentNode = currentNode.nextNode; currentNode = currentNode.nextNode;
} while (currentNode != head); } while (currentNode != head);
} }

32
data-structures/src/test/java/com/baeldung/circularlinkedlist/CircularLinkedListUnitTest.java
View File

@ -1,10 +1,10 @@
package com.baeldung.circularlinkedlist; package com.baeldung.circularlinkedlist;
import org.junit.Test;
import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue; import static org.junit.Assert.assertTrue;
import org.junit.Test;
public class CircularLinkedListUnitTest { public class CircularLinkedListUnitTest {
@Test @Test
@ -23,7 +23,7 @@ public class CircularLinkedListUnitTest {
} }
@Test @Test
public void givenACircularLinkedList_WhenDeletingElements_ThenListDoesNotContainThoseElements() { public void givenACircularLinkedList_WhenDeletingInOrderHeadMiddleTail_ThenListDoesNotContainThoseElements() {
CircularLinkedList cll = createCircularLinkedList(); CircularLinkedList cll = createCircularLinkedList();
assertTrue(cll.containsNode(13)); assertTrue(cll.containsNode(13));
@ -39,6 +39,32 @@ public class CircularLinkedListUnitTest {
assertFalse(cll.containsNode(46)); assertFalse(cll.containsNode(46));
} }
@Test
public void givenACircularLinkedList_WhenDeletingInOrderTailMiddleHead_ThenListDoesNotContainThoseElements() {
CircularLinkedList cll = createCircularLinkedList();
assertTrue(cll.containsNode(46));
cll.deleteNode(46);
assertFalse(cll.containsNode(46));
assertTrue(cll.containsNode(1));
cll.deleteNode(1);
assertFalse(cll.containsNode(1));
assertTrue(cll.containsNode(13));
cll.deleteNode(13);
assertFalse(cll.containsNode(13));
}
@Test
public void givenACircularLinkedListWithOneNode_WhenDeletingElement_ThenListDoesNotContainTheElement() {
CircularLinkedList cll = new CircularLinkedList();
cll.addNode(1);
cll.deleteNode(1);
assertFalse(cll.containsNode(1));
}
private CircularLinkedList createCircularLinkedList() { private CircularLinkedList createCircularLinkedList() {
CircularLinkedList cll = new CircularLinkedList(); CircularLinkedList cll = new CircularLinkedList();