# [155. Min Stack](https://leetcode.com/problems/min-stack/)

## 题目

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.



Example:

```c
MinStack minStack = new MinStack();
minStack.push(-2);
minStack.push(0);
minStack.push(-3);
minStack.getMin();   --> Returns -3.
minStack.pop();
minStack.top();      --> Returns 0.
minStack.getMin();   --> Returns -2.
```

## 题目大意

这道题是一个数据结构实现题。要求实现一个栈的类，实现 push()、pop()、top()、getMin()。


## 解题思路

按照题目要求实现即可。