/*

* @lc app=leetcode id=155 lang=java

*

* [155] Min Stack

* 创造一个辅助stack MinStack，用来同步储存最小值

*/

// @lc code=start

import java.util.Stack;

class MinStack {

Stack<Integer> stack;

Stack<Integer> minStack;

int min;

public MinStack() {

stack = new Stack<>();

minStack = new Stack<>();

min = Integer.MAX_VALUE;

}

public void push(int val) {

stack.push(val);

if (val <= min) {

minStack.push(val);

min = val;

}

}

public void pop() {

int popedValue = stack.pop();

if (popedValue == min) {

minStack.pop();

if (!minStack.isEmpty()) {

min = minStack.peek();

} else {

min = Integer.MAX_VALUE; //重置最小值

}

}

}

public int top() {

int value = stack.peek();

return value;

}

public int getMin() {

return min;

}

}

/**

* Your MinStack object will be instantiated and called as such:

* MinStack obj = new MinStack();

* obj.push(val);

* obj.pop();

* int param_3 = obj.top();

* int param_4 = obj.getMin();

*/

// @lc code=end