index.js

var MinStack = function() {
    this.stack = []
};

/** 
 * @param {number} x
 * @return {void}
 */
MinStack.prototype.push = function(x) {
    let min = this.stack.length === 0 ? x : this.stack[this.stack.length - 1].min
    this.stack.push({val: x, min: Math.min(min, x)})
};

/**
 * @return {void}
 */
MinStack.prototype.pop = function() {
    if(this.stack.length > 0){
        this.stack.pop()
    }
};

/**
 * @return {number}
 */
MinStack.prototype.top = function() {
    if(this.stack.length > 0) {
        return this.stack[this.stack.length - 1].val
    }
};

/**
 * @return {number}
 */
MinStack.prototype.getMin = function() {
    if(this.stack.length > 0) {
        return this.stack[this.stack.length - 1].min
    }
};
/** 
 * Your MinStack object will be instantiated and called as such:
 * var obj = Object.create(MinStack).createNew()
 * obj.push(x)
 * obj.pop()
 * var param_3 = obj.top()
 * var param_4 = obj.getMin()
 */

module.exports = {
    id:'155',
    title:'Min Stack',
    url:'https://leetcode.com/problems/min-stack/#/description',
    difficulty:'easy',
};