cf B. Dima and To-do List

http://codeforces.com/contest/366/problem/B

从0到k枚举起点，然后i+k判断是不是i+k>=n如果是i=(i+k)%n;否则i=i+k;

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #define maxn 200010
 5 using namespace std;
 6 const int inf=1<<29;
 7 
 8 int n,k;
 9 int a[maxn];
10 bool vis[maxn];
11 
12 int main()
13 {
14     while(scanf("%d%d",&n,&k)!=EOF)
15     {
16         for(int i=0; i<n; i++)
17         {
18             scanf("%d",&a[i]);
19         }
20         __int64 min1=inf;
21         int c;
22         for(int j=0; j<k; j++)
23         {
24             __int64 sum=(__int64)a[j];
25             int i=j;
26             while(1)
27             {
28                 if(i+k>=n)
29                 {
30                     i=(i+k)%n;
31                 }
32                 else i=i+k;
33                 if(i==j) break;
34                 sum+=a[i];
35             }
36             if(sum<min1)
37             {
38                 min1=sum;
39                 c=j;
40             }
41         }
42         printf("%d\n",c+1);
43     }
44     return 0;
45 }

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