Design stack supporting push, pop, top, and retrieving minimum in O(1).
Sample Input:
["MinStack","push","push","push","getMin","pop","top","getMin"], [[],[-2],[0],[-3],[],[],[],[]]
Sample Output:
[null,null,null,null,-3,null,0,-2]
Hints
Hint 1
Use auxiliary stack to track minimums
Hint 2
Push current minimum with each element
Hint 3
Pop from both stacks when removing
