3.2 How would you design a stack which, in addition to push and pop, also has a function min which returns the minimum element? Push, pop and min should all operate in O(1) time.
LeetCode上的原题，请参见我之前的博客Min Stack 最小栈。
本文转自博客园Grandyang的博客，原文链接：最小栈[CareerCup] 3.2 Min Stack ，如需转载请自行联系原博主。
