leetcode155

public class MinStack
    {
        Stack<int> S = new Stack<int>();
        /** initialize your data structure here. */

        int min = int.MaxValue;

        public MinStack()
        {

        }

        public void Push(int x)
        {
            if (S.Count > 0)
            {
                if (x < min)
                {
                    min = x;
                }
            }
            else
            {
                min = x;
            }
            S.Push(x);
        }

        public void Pop()
        {
            if (S.Count > 0)
            {
                var top = S.Pop();
                if (top == min && S.Count > 0)
                {
                    min = S.Min();
                }
            }
        }

        public int Top()
        {
            return S.Peek();
        }

        public int GetMin()
        {
            return min;
        }
    }

/**
 * Your MinStack object will be instantiated and called as such:
 * MinStack obj = new MinStack();
 * obj.Push(x);
 * obj.Pop();
 * int param_3 = obj.Top();
 * int param_4 = obj.GetMin();
 */

https://leetcode.com/problems/min-stack/#/description