Queues using Stacks
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class Node {
constructor(data) {
this.data = data;
this.next = null;
}
}
class Queue {
constructor() {
this.first = null;
this.last = null;
this.length = 0;
}
enqueue(value) {
const newNode = new Node(value);
if( this.length === 0) {
this.first = newNode;
this.last = newNode;
}
else {
this.last.next = newNode;
this.last = newNode;
}
this.length++;
}
peek() {
return this.first;
}
dequeue() {
if(this.length === 0) {
return null;
}
if(this.first === this.last) {
this.last = null;
}
const temp = this.first;
this.first = this.first.next;
this.length--;
return temp;
}
isEmpty() {
return (this.length === 0) ? true : false;
}
}
JavaScript
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