栈的应用场景(三)

1.题目

2.画图分析

3.代码实现

package Stack;import java.util.Stack;
public class MinStack {private Stack <Integer> stack;private Stack <Integer> MinStack;public MinStack() {stack = new Stack<>();MinStack = new Stack<>();}public void push(int val) {//普通栈只要是元素都得放//最小栈 如果为空,放元素.如果不为空且要放的元素比栈顶元素小,也要放stack.push(val);if(MinStack.empty()){MinStack.push(val);}else{int peek = MinStack.peek();if(val <= peek){MinStack.push(val);}}}public void pop() {int val = stack.pop();//如果最小栈不为空if(!MinStack.empty()){if(val == MinStack.peek()){MinStack.pop();}}}//获取普通栈的栈顶public int top() {return stack.peek();}public int getMin() {if(!MinStack.empty()){return MinStack.peek();}return -1;}
}