What is Stack

Stack = LIFO = DFS

Stack is LIFO (Last In First Out).

• Add to top, remove from top.

// Add to the BACK of the array:
.append() // py
.push() // js

// Removes from the BACK of the array:
.pop() // js & py

Stack allows for backtracking which allows implementation of depth first search.

What is Queue

Queue = FIFO = BFS

Queue is FIFO (First in First out)

• First in line is first to be served.

// Add to the BACK of the array
.append() // py
.push() // js

// Remove from the FRONT of the array
.shift() // js
.remove() OR .pop(0) // py

• To search breadth first, top nodes are added to the array first.
• They are then popped in added order to traverse in natural breadth-first sequential order.

Enqueue/Dequeue

Enqueue

• unshift/first = adds to beginning
• push/last = adds to end

Dequeue

• shift/first = removes from beginning
• pop/last = removes from end