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Minor code style fixes for DoublyLinkedList.

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This commit is contained in:
Oleksii Trekhleb
2018-07-05 15:44:25 +03:00
parent a72fda4dfd
commit d0499d2544
2 changed files with 21 additions and 6 deletions
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24
src/data-structures/doubly-linked-list/DoublyLinkedList.js
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@ -78,38 +78,44 @@ export default class DoublyLinkedList {
let deletedNode = null;
let currentNode = this.head;
do {
while (currentNode) {
if (this.compare.equal(currentNode.value, value)) {
deletedNode = currentNode;
if (deletedNode === this.head) {
// If HEAD is going to be deleted...
// Set head to second node, which will become new head.
this.head = deletedNode.next;
// Set new head's previous to null
// Set new head's previous to null.
if (this.head) {
this.head.previous = null;
}
// If all the nodes in list has same value that is passed as argument
// then all nodes will get deleted, therefore tail needs to be updated
// then all nodes will get deleted, therefore tail needs to be updated.
if (deletedNode === this.tail) {
this.tail = null;
}
} else if (deletedNode === this.tail) {
// set tail to second last node, which will become new tail
// If TAIL is going to be deleted...
// Set tail to second last node, which will become new tail.
this.tail = deletedNode.previous;
this.tail.next = null;
} else {
// If MIDDLE node is going to be deleted...
const previousNode = deletedNode.previous;
const nextNode = deletedNode.next;
previousNode.next = nextNode;
nextNode.previous = previousNode;
}
}
currentNode = currentNode.next;
} while (currentNode);
}
return deletedNode;
}
@ -149,8 +155,12 @@ export default class DoublyLinkedList {
*/
deleteTail() {
if (!this.tail) {
// No tail to delete.
return null;
} else if (this.head === this.tail) {
}
if (this.head === this.tail) {
// There is only one node in linked list.
const deletedTail = this.tail;
this.head = null;
this.tail = null;
@ -158,7 +168,9 @@ export default class DoublyLinkedList {
return deletedTail;
}
// If there are many nodes in linked list...
const deletedTail = this.tail;
this.tail = this.tail.previous;
this.tail.next = null;

3
src/data-structures/linked-list/LinkedList.js
View File

@ -128,6 +128,7 @@ export default class LinkedList {
*/
deleteTail() {
if (this.head === this.tail) {
// There is only one node in linked list.
const deletedTail = this.tail;
this.head = null;
this.tail = null;
@ -135,6 +136,7 @@ export default class LinkedList {
return deletedTail;
}
// If there are many nodes in linked list...
const deletedTail = this.tail;
// Rewind to the last node and delete "next" link for the node before the last one.
@ -148,6 +150,7 @@ export default class LinkedList {
}
this.tail = currentNode;
return deletedTail;
}