Queue

A FIFO (First In, First Out) data structure. Used in BFS, task scheduling, and message passing. Enqueue to back, dequeue from front.

Syntax

dsa

enqueue(item)  // add to back
dequeue()       // remove from front
peek()          // view front

Example

dsa

// JavaScript using array (inefficient) or linked list:
const queue = [];
queue.push("A");    // enqueue
queue.push("B");
queue.push("C");
queue.shift();      // dequeue: "A"
console.log(queue); // ["B", "C"]
// Note: shift() is O(n); use a proper deque for O(1)