LeetCode -- Min Stack

public class MinStack {
    private Stack<int> _stack ;
	private int? _min;
	public MinStack(){
		_stack = new Stack<int>();
	}
    public void Push(int x) {
        if(!_min.HasValue || x < _min){
			_min = x;
		}
		_stack.Push(x);
    }


    public void Pop() {
        var x = _stack.Pop();
		if (x == _min){
			if(_stack.Count > 0){
				_min = _stack.Min();
			}
			else{
				_min = null;
			}
		}
    }


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


    public int GetMin() {
        return _min.Value;
    }
}

LeetCode -- Min Stack

原文：http://blog.csdn.net/lan_liang/article/details/49962363