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(vector<int>& height) {
if (height.size() == 0)
return 0;
int pivot = 0;
int maxValue = 0;
for (int i=0; i<height.size(); i++)
{
if (height[i] > maxValue)
{
maxValue = height[i];
pivot = i;
}
}
int curSum = 0;
int curMax = height[0];
for (int i=1; i<pivot; i++)
{
if (curMax > height[i])
curSum += (curMax-height[i]);
else if (curMax < height[i])
curMax = height[i];
}
curMax = height[height.size()-1];
for (int i=height.size()-2; i>pivot; i--)
{
if (curMax > height[i])
curSum += (curMax-height[i]);
else if (curMax < height[i])
curMax = height[i];
}
return curSum;
}
};