#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
 
 
int trap(int* height, int heightSize) 
{
	int ans = 0;
	int left = 0;
	int right = heightSize - 1;
	int premax = 0;
	int max = 0;
	int i = 0;
	while (left < right)
	{
		if (height[left] > height[right] && height[right] > max)
		{
			premax = max;
			max = height[right];
			for (i = left + 1; i <= right - 1; i++)
			{
				if (height[i] <= premax)
					ans = ans - premax + max;
				if (height[i] > premax&&height[i] < max)
					ans = ans + max - height[i];
			}
			right--;
		}
 
		if (height[left] <= height[right] && height[left] > max)
		{
			premax = max;
			max = height[left];
			for (i = left + 1; i <= right - 1; i++)
			{
				if (height[i] <= premax)
					ans = ans - premax + max;
				if (height[i] > premax&&height[i] < max)
					ans = ans + max - height[i];
			}
			left++;
		}
 
		if (height[left] <= max)
		{
			left++;
		}
		if (height[right] <= max)
		{
			right--;
		}
	}
	return ans;
}
 
int main()
{
	int height[] = { 0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1 };
	int heightSize = sizeof(height) / sizeof(int);
	int ans = trap(height, heightSize);
	printf("%d", ans);
}

牛不牛逼？