1 class Solution {
2 public:
3 int trap(int A[], int n) {
4 // IMPORTANT: Please reset any member data you declared, as
5 // the same Solution instance will be reused for each test case.
6 int * lr = new int [n];
7 int last = 0;
8 for (int i=0; i<n; i++){
9 if (A[i]<last)
10 lr[i]=last-A[i];
11 else{
12 lr[i] = 0;
13 last = A[i];
14 }
15 }
16 int * rl = new int [n];
17 last = 0;
18 for (int i=n-1; i>=0; i--){
19 if (A[i]<last)
20 rl[i]=last-A[i];
21 else{
22 rl[i] = 0;
23 last = A[i];
24 }
25 }
26 int sum = 0;
27 for (int i=0; i<n; i++)
28 sum += lr[i]<rl[i]?lr[i]:rl[i];
29 delete []lr;
30 delete []rl;
31 return sum;
32 }
33 };
