155.最小栈.js

/*
 * @lc app=leetcode.cn id=155 lang=javascript
 *
 * [155] 最小栈
 *
 * https://leetcode-cn.com/problems/min-stack/description/
 *
 * algorithms
 * Easy (55.63%)
 * Likes:    935
 * Dislikes: 0
 * Total Accepted:    251.9K
 * Total Submissions: 442.3K
 * Testcase Example:  '["MinStack","push","push","push","getMin","pop","top","getMin"]\n[[],[-2],[0],[-3],[],[],[],[]]'
 *
 * 设计一个支持 push ，pop ，top 操作，并能在常数时间内检索到最小元素的栈。
 * 
 * 
 * push(x) —— 将元素 x 推入栈中。
 * pop() —— 删除栈顶的元素。
 * top() —— 获取栈顶元素。
 * getMin() —— 检索栈中的最小元素。
 * 
 * 
 * 
 * 
 * 示例:
 * 
 * 输入：
 * ["MinStack","push","push","push","getMin","pop","top","getMin"]
 * [[],[-2],[0],[-3],[],[],[],[]]
 * 
 * 输出：
 * [null,null,null,null,-3,null,0,-2]
 * 
 * 解释：
 * MinStack minStack = new MinStack();
 * minStack.push(-2);
 * minStack.push(0);
 * minStack.push(-3);
 * minStack.getMin();   --> 返回 -3.
 * minStack.pop();
 * minStack.top();      --> 返回 0.
 * minStack.getMin();   --> 返回 -2.
 * 
 * 
 * 
 * 
 * 提示：
 * 
 * 
 * pop、top 和 getMin 操作总是在 非空栈 上调用。
 * 
 * 
 */

// @lc code=start
/**
 * initialize your data structure here.
 */
var MinStack = function() {
  this.stack=[]
  this.resStack =[Infinity]
};

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

/**
 * @return {void}
 */
MinStack.prototype.pop = function() {
  this.stack.pop()
  this.resStack.pop();
};

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

/**
 * @return {number}
 */
MinStack.prototype.getMin = function() {
  return this.resStack[this.resStack.length-1]
};

/**
 * Your MinStack object will be instantiated and called as such:
 * var obj = new MinStack()
 * obj.push(val)
 * obj.pop()
 * var param_3 = obj.top()
 * var param_4 = obj.getMin()
 */
// @lc code=end