标签：
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.
The above elevation map is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped. Thanks Marcos for contributing this image!
class Solution { public: int trap(int A[], int n) { if (A==NULL||n<3) return 0; int maxleft=0; int maxright=0; int i=0,j=n-1; int sum=0; while(i<j) { if (maxleft<A[i]) { maxleft=A[i]; } if (maxright<A[j]) { maxright=A[j]; } if (maxleft<=maxright) { sum+=maxleft-A[i]; i++; } else { sum+=maxright-A[j]; j--; } } return sum; } };
leetcode[42]Trapping Rain Water
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原文地址：http://www.cnblogs.com/Vae98Scilence/p/4283576.html
