// Source : https://leetcode.com/problems/min-stack/description/
// Author : Tianming Cao
// Date : 2018-02-02
/**********************************************************************************
* 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:
* 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.
*
**********************************************************************************/
package minStack;
import java.util.Stack;
public class MinStack {
public Stack