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153 | class DoublyLinkedList {
constructor() {
this.head = null;
this.tail = null;
this.length = 0;
}
push(val) {
const 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;
let 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;
let 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) {
const 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;
let curr = null;
if (index <= this.length / 2) {
let count = 0;
curr = this.head;
while (count !== index) {
curr = curr.next;
count++;
}
} else {
let count = this.length - 1;
curr = this.tail;
while (count !== index) {
curr = curr.prev;
count--;
}
}
return curr;
}
set(index, val) {
let foundNode = this.get(index);
if (foundNode) {
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, val];
const newNode = new Node(val);
let prev = this.get(index - 1);
let next = prev.next;
(prev.next = newNode), (newNode.prev = prev);
(newNode.next = next), (next.prev = newNode);
this.length++;
return true;
}
remove(index) {
if (index < 0 || index >= this.length) return undefined;
if (index === 0) return this.shift();
if (index === this.length) return this.pop();
let removedNode = this.get(index);
removedNode.prev.next = removedNode.next;
removedNode.next.prev = removedNode.prev;
removedNode.next = null;
removedNode.prev = null;
this.length--;
return removedNode;
}
print() {
const arr = [];
let curr = this.head;
while (curr) {
arr.push(curr.val);
curr = curr.next;
}
console.log(arr);
}
}
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