Trapping Rain Water

Given n non-negative integers representing an elevation map where the width of each bar are 1, compute how much WA ter It is the 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 the Rain Water (blue section) is being trapped. Thanks Marcos for contributing this image!

Analyse:the water can trapped equals to the min (Left[i], right[i])-height[i], whereas Left[i] and Right[i] is the LA Rgest number of the left and right part of the number.

Runtime:8ms.

1 classSolution {2  Public:3     intTrap (vector<int>&height) {4         intn =height.size ();5         if(N <=1)return 0;6         7         int*left =New int[n];8         intmax = height[0];9          for(inti =1; I < n-1; i++) {//Find the largest of the left of a elementTenLeft[i] =Max; One             if(Height[i] >max) AMax =Height[i]; -         } -max = Height[n-1]; the         intresult =0; -          for(intj = N-2; J >=0; j--){ -             intdiff = min (max, left[j])-height[j];//The water trapped at index i -             if(diff >0)  +Result + =diff; -             if(Height[j] >max) +Max =Height[j]; A         } at         returnresult; -     } -};

Trapping Rain Water