JZ-020- stack containing min function

Stack containing min function

Title description

To define the data structure of the stack, please implement a min function (time complexity should be O(1)) that can get the smallest element contained in the stack in this type.

topic link : contains the min function stack

Code

import java.util.Stack;

/**
 * 标题：包含 min 函数的栈
 * 题目描述
 * 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））。
 * 题目链接：
 * https://www.nowcoder.com/practice/4c776177d2c04c2494f2555c9fcc1e49?tpId=13&&tqId=11173&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking
 */
public class Jz20 {

    private Stack<Integer> datas = new Stack<Integer>();
    private Stack<Integer> minDatas = new Stack<Integer>();

    public void push(int node) {
        datas.push(node);
        if (minDatas.isEmpty()) {
            minDatas.push(node);
        } else if (node <= minDatas.peek()) {
            minDatas.push(node);
        }
    }

    public void pop() {
        int popData = datas.pop();
        if (popData == minDatas.peek()) {
            minDatas.pop();
        }
    }

    public int top() {
        return datas.peek();
    }

    public int min() {
        return minDatas.peek();
    }
}

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