一、题目内容

二、题解

解法1：

思路

双栈

代码

class MinStack {
    LinkedList<Integer> stack, minStack;
    /**
        * initialize your data structure here.
        */
    public MinStack() {
        stack = new LinkedList<Integer>();
        minStack = new LinkedList<Integer>();
    }
    public void push(int x) {
        stack.addLast(x);
        if (minStack.isEmpty() || minStack.getLast() >= x) {
            minStack.addLast(x);
        }
    }
    public void pop() {
        if (!stack.isEmpty()) {
            int temp = stack.removeLast();
            if (!minStack.isEmpty() && minStack.getLast() == temp) {
                minStack.removeLast();
            }
        }
    }
    public int top() {
        //可以不判空
        return stack.getLast();
    }
    public int min() {
        return minStack.getLast();
    }
}