问题描述: 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], return 6. 算法分析:观察下就可以发现被水填满后的形状是先升后降的塔形,因此,先遍历一…