stack containing min function
Topic:
Define the data structure of the stack, please implement a min function in this type that can get the smallest element contained in the stack (the time complexity should be O(1)).
Note: Make sure that the test will not call pop() or min() or top() on the stack when the stack is empty.
Code:
package com.sjsq.test;
/**
* @author shuijianshiqing
* @date 2020/5/22 22:20
*/
import java.util.Stack;
/**
* 定义栈的数据结构，请在该类型中实现一个能够得到栈中所含最小元素
* 的min函数（时间复杂度应为O（1））。
* 注意：保证测试中不会当栈为空的时候，对栈调用pop()或者min()或者top()方法。
*/
public class Solution {
Stack<Integer> stack = new Stack<Integer>();
// 设置一个临时栈来存放被pop出的数据
Stack<Integer> tmp = new Stack<Integer>();
public void push(int node) {
stack.push(node);
}
public void pop() {
stack.pop();
}
public int top() {
return stack.peek();
}
public int min() {
int min = Integer.MAX_VALUE;
// 出栈
while(stack.isEmpty() != true){
int node = stack.pop();
if(min > node){
min = node;
}
tmp.push(node);
}
// 进栈
while(tmp.isEmpty() != true){
stack.push(tmp.pop());
}
return min;
}
}