1 #include <stdio.h>
2
3 int trap(int* height, int heightSize)
4 {
5 int rains = 0;
6 if(heightSize==0)
7 return rains;
8 int leftmax = 0,rightmax = 0;
9 int left = 0,right = heightSize-1;
10 while(left<right)
11 {
12 leftmax = leftmax>height[left]?leftmax:height[left];
13 rightmax = rightmax>height[right]?rightmax:height[right];
14
15 if(leftmax<rightmax)
16 {
17 rains += leftmax-height[left];
18 left ++;
19 }
20 else
21 {
22 rains += rightmax-height[right];
23 right --;
24 }
25 }
26 return rains;
27 }
28
29 int main()
30 {
31 int heightSize;
32 while(~scanf("%d",&heightSize))
33 {
34 int height[heightSize];
35 int i;
36 for(i = 0;i < heightSize;i ++)
37 {
38 scanf("%d",&height[i]);
39 }
40 int result = trap(height, heightSize);
41 printf("%d\n",result);
42 }
43 return 0;
44 }
