forked from akshitagit/JavaScript
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathDoublyLinkedList.js
More file actions
116 lines (112 loc) · 2.97 KB
/
DoublyLinkedList.js
File metadata and controls
116 lines (112 loc) · 2.97 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
class Node {
constructor(val) {
this.val = val;
this.next = null;
this.prev = null;
}
}
class DoublyLinkedList {
constructor() {
this.head = null;
this.tail = null;
this.length = 0;
}
push(val) {
var newNode = new Node(val);
if (this.length === 0) {
this.head = newNode;
this.tail = newNode;
} else {
this.tail.next = newNode;
newNode.prev = this.tail;
this.tail = newNode;
}
this.length++;
return this;
}
pop() {
if (!this.head) return undefined;
var poppedNode = this.tail;
if (this.length === 1) {
this.head = null;
this.tail = null;
} else {
this.tail = poppedNode.prev;
this.tail.next = null;
poppedNode.prev = null;
}
this.length--;
return poppedNode;
}
shift() {
if (this.length === 0) return undefined;
var oldHead = this.head;
if (this.length === 1) {
this.head = null;
this.tail = null;
} else {
this.head = oldHead.next;
this.head.prev = null;
oldHead.next = null;
}
this.length--;
return oldHead;
}
unshift(val) {
var newNode = new Node(val);
if (this.length === 0) {
this.head = newNode;
this.tail = newNode;
} else {
this.head.prev = newNode;
newNode.next = this.head;
this.head = newNode;
}
this.length++;
return this;
}
get(index) {
if (index < 0 || index >= this.length) return null;
var count, current;
if (index <= this.length / 2) {
count = 0;
current = this.head;
while (count !== index) {
current = current.next;
count++;
}
} else {
count = this.length - 1;
current = this.tail;
while (count !== index) {
current = current.prev;
count--;
}
}
return current;
}
set(index, val) {
var foundNode = this.get(index);
if (foundNode != null) {
foundNode.val = val;
return true;
}
return false;
}
insert(index, val) {
if (index < 0 || index > this.length) return false;
if (index === 0) return !!this.unshift(val);
if (index === this.length) return !!this.push(val);
var newNode = new Node(val);
var beforeNode = this.get(index - 1);
var afterNode = beforeNode.next;
(beforeNode.next = newNode), (newNode.prev = beforeNode);
(newNode.next = afterNode), (afterNode.prev = newNode);
this.length++;
return true;
}
}
var list = new DoublyLinkedList();
list.push("Harry");
list.push("Ron");
list.push("Hermione");