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!
双指针，需要把情况考虑全。
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class
Solution {public: int
trap(int
A[], int
n) { int
result = 0; int
l = 0,r = n-1; while(A[l]==0)l++; while(A[r]==0)r--; int
h = 0; h = min(A[l],A[r]); while(l < r) { if(A[l] <= h) { result += h - A[l]; l++; } else
if(A[r] < h) { result += h - A[r]; r--; } else
if(A[l] > h && A[r] == h) { r--; } else
if(A[r] > h && A[l] == h) { l++; } else
if(A[l]>h &&A[r]>h) { h = min(A[l],A[r]); } } return
result; }}; |
Trapping Rain Water,布布扣,bubuko.com
原文：http://www.cnblogs.com/pengyu2003/p/3675706.html