JZ20 包含 min 函数的栈
https://www.nowcoder.com/practice/4c776177d2c04c2494f2555c9fcc1e49
这题关键就是添加一个最小栈同步插入弹出数据
import java.util.Stack;
public class Solution {
private Stack<Integer> dataStack = new Stack<>();
private Stack<Integer> minStack = new Stack<>();
public void push(int node) {
dataStack.push(node);
if (minStack.empty() || minStack.peek() > node) {
minStack.push(node);
} else {
// 这里是使辅助栈和数据栈个数保持一致
minStack.push(minStack.peek());
}
}
public void pop() {
dataStack.pop();
minStack.pop();
}
public int top() {
return dataStack.peek();
}
public int min() {
return minStack.peek();
}
}