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162 | class SinglyLinkedList {
constructor() {
this.head = null;
this.tail = null;
this.length = 0;
}
push(val) {
const newNode = new Node(val);
if (!this.head) {
this.head = newNode;
this.tail = this.head;
} else {
this.tail.next = newNode;
this.tail = newNode;
}
this.length++;
return this;
}
pop() {
if (!this.head) return undefined;
let poppedNode = this.head;
let newTail = poppedNode;
if (this.length === 1) {
this.head = null;
this.tail = null;
} else {
while (poppedNode.next) {
newTail = poppedNode;
poppedNode = poppedNode.next;
}
this.tail = newTail;
this.tail.next = 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;
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 {
newNode.next = this.head;
this.head = newNode;
}
this.length++;
return this;
}
get(index) {
if (index < 0 || index >= this.length) return null;
let count = 0;
let curr = this.head;
while (count !== index) {
curr = curr.next;
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.next = next;
this.length++;
return true;
}
remove(index) {
if (index < 0 || index >= this.length) return undefined;
if (index === 0) return this.shift();
if (index === this.length - 1) return this.pop();
let prev = this.get(index - 1);
let removedNode = prev.next;
prev.next = removedNode.next;
removedNode.next = null;
this.length--;
return removedNode;
}
reverse() {
let node = this.head;
this.head = this.tail;
this.tail = node;
let oldNext;
let prev = null;
for (let i = 0; i < this.length; i++) {
oldNext = node.next;
node.next = prev;
prev = node;
node = oldNext;
}
return this;
}
print() {
const arr = [];
let curr = this.head;
while (curr) {
arr.push(curr.val);
curr = curr.next;
}
console.log(arr);
}
}
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