03-02 - Stack Min [Cracking the Coding Interview]

const { Stack } = require('../../utils')

const StackWithMin = (function () {
	let minStack = new Stack()

	class StackWithMin extends Stack {
		constructor() {
			super()
		}

		min() {
			return minStack.peek()
		}

		push(item) {
			super.push(item)
			//Set item as new min if min is null or if item <= min
			if (minStack.peek() === null || item <= minStack.peek()) {
				minStack.push(item)
			}
		}

		pop() {
			const item = super.pop()

			// pop item from min stack if min === item
			if (minStack.peek() === item) minStack.pop()

			return item
		}
	}

	return StackWithMin
})()

// Tests

const stack = new StackWithMin()
stack.push(3)
stack.push(1)

console.log('min: ', stack.min(), stack.stackToString())
stack.push(0)
stack.push(4)
console.log('min: ', stack.min(), stack.stackToString())
stack.push(-1)
console.log('min: ', stack.min(), stack.stackToString())
stack.push(0)
stack.push(-1)
console.log('min: ', stack.min(), stack.stackToString())
stack.pop()
stack.pop()
console.log('min: ', stack.min(), stack.stackToString())
stack.pop()
console.log('min: ', stack.min(), stack.stackToString())
console.log(stack.printStack())