[leetcode] 155. 最小栈

LeetCode.155 最小栈

public class MinStack {

    Stack<Integer> elements;
    Stack<Integer> min;

    MinStack() {
        elements = new Stack<Integer>();
        min = new Stack<Integer>();
    }

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

    public void push(int x) {
        elements.push(x);
        if (min.isEmpty() || getMin() > x) {
            min.push(x);
        } else {
            min.push(getMin());
        }
    }

    public int pop() {
        min.pop();
        return elements.pop();
    }

    int top() {
        return elements.peek();
    }
}