Arithmetic Sequence

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 const long long  maxn = 100005;
 6 long long  A[maxn];
 7 int main()
 8 {
 9     long long flag,n, d1, d2;
10     long long sum, cnt;
11     while(~scanf("%I64d %I64d %I64d", &n, &d1, &d2))
12     {
13         for(int i = 0; i < n; i++)
14         {
15             scanf("%I64d", &A[i]);
16         }
17 
18         sum = 0, flag = 0, cnt = 0;
19 
20         for(int i = 1; i < n; i++)
21         {
22             if(A[i]-A[i-1] == d1 && flag == 0)
23             {
24                 cnt ++;
25                 continue;
26             }
27             if(A[i]-A[i-1] == d2)
28             {
29                 flag = 1;
30                 cnt ++;
31                 continue;
32             }
33             //printf("cnt = %d\n", cnt);
34             sum += (1+cnt)*cnt/2;
35             if(cnt != 0) i--;
36             cnt = 0;
37             flag = 0;
38         }
39         sum += (1+cnt)*cnt/2;
40         //if (d1!=d2)
41         printf("%I64d\n", sum + n);
42         //else printf("%I64d\n",n);
43     }
44     return 0;
45 }
46 
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