剑指 Offer 30. 包含min函数的栈

Stack.peek()只取值 不会删掉值 。

class MinStack {
 	private Stack<Integer> dataStack; // 数据栈
    private Stack<Integer> minStack; // 辅助栈，记录每次有元素进栈后或者出栈后，元素的最小值

    /** initialize your data structure here. */
    public MinStack() {
        dataStack= new Stack <>();
        minStack= new Stack <>();
    }
    
    public void push(int x) {
        if(minStack.isEmpty()||minStack.peek()>x){
            minStack.push(x);
        }else{
            minStack.push(minStack.peek());
        }
        dataStack.push(x);
    }
    
    public void pop() {
        dataStack.pop();
        minStack.pop();
    }
    
    public int top() {
        return dataStack.peek();
    }
    
    public int min() {
        return minStack.peek();
    }
}