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]
, return6
.
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(vector<int>& height) {
int result = 0;
int max_index = 0;
int n = height.size();
for(int i=0;i<n;i++)
{
if(height[max_index]<height[i])
{
max_index = i;
}
}
int second = 0;
for(int i=0;i<max_index;i++)
{
if(second>height[i])
result += second - height[i];
else
second = height[i];
}
second = 0;
for(int i = n-1;i>max_index;i--)
{
if(second>height[i])
result += second - height[i];
else
second = height[i];
}
return result;
}
};
