Stack.md

Stack

A stack is a data structure that stores a collection of data values in a LIFO (last in, first out) order.
A stack operations can only occur through one of its end, referred as the top of the stack.
The implementation could be an array-like (static and contiguous) or a linked-list-like (dynamic and dis-contiguous).

Stack's Common Operations

Push

Add item to the top of the stack.

Example

let stack = [4, 1, 0, 2];
stack.push(5);
// stack is now [5, 4, 1, 0, 2]

Pop

Remove item from the top of the stack.

Example

let stack = [4, 1, 0, 2];
let top = stack.pop();
// top is 4
// stack is now [1, 0, 2]

Peek

Some programming languages provides peek method to allow checking the value of the current top without removing the value from the stack.

Example

let stack = [4, 1, 0, 2];
let currentHead = stack.peek();
// currentHead is 4
// stack remains [4, 1, 0, 2]