这题放上来是因为自己第一回见到这种题,觉得它好玩儿 =) Trapping Rain Water Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining. For example, Given [0,1,0,2,1,0,1,3,2,1,2,1], retu…