Min Stack

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要求

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

push(x) – Push element x onto stack.

pop() – Removes the element on top of the stack.

top() – Get the top element.

getMin() – Retrieve the minimum element in the stack.

标签：Stack, Data Structure

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我的提交：

    public class MinStack {        Stack<int> stack;        Stack<int> minStack;        public MinStack()            {                stack = new Stack<int>();                minStack = new Stack<int>();            }        public void Push(int x) {            stack.Push(x);                if (minStack.Count == 0)                    minStack.Push(x);                else if(minStack.Peek() >= x)                    minStack.Push(x);        }        public void Pop() {            if(stack!=null)                {                    int ele = stack.Pop();                    if (ele == minStack.Peek())                        minStack.Pop();                }        }        public int Top() {            return stack.Peek();        }        public int GetMin() {            return minStack.Peek();        }    }

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注意事项：

• 使用两个栈，1st栈正常使用，2nd栈为最小栈，当新加入的元素值elem小于等于正常栈栈顶元素时，elem压入正常栈同时压入最小栈
• 对于最小栈，栈为空时（初始状态），新元素elem必加入栈中

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P.S：欢迎各位学友都对我的解法的不足之处作出建议！