poj 1961 Period

 1 #include<cstdio>
 2 #include<cstring>
 3 #define N 1000005
 4 #define LL long long
 5 #define inf 0x3f3f3f3f
 6 using namespace std;
 7 inline int ra()
 8 {
 9     int x=0,f=1; char ch=getchar();
10     while (ch<‘0‘ || ch>‘9‘) {if (ch==‘-‘) f=-1; ch=getchar();}
11     while (ch>=‘0‘ && ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
12     return x*f;
13 }
14 int n,cas,fail[N];
15 char ch[N];
16 int main()
17 {
18     while (scanf("%d",&n))
19     {
20         if (!n) break;
21         scanf("%s",ch+1);
22         int fix=0;
23         for (int i=2; i<=n; i++)
24         {
25             while (ch[i]!=ch[fix+1] && fix) fix=fail[fix];
26             if (ch[fix+1]==ch[i]) fix++; fail[i]=fix;
27         }
28         printf("Test case #%d\n",++cas);
29         for (int i=2; i<=n; i++)
30         {
31             int x=i-fail[i];
32             if (i%x || x==i) continue;
33             printf("%d %d\n",i,i/x);
34         }
35         printf("\n");
36     }
37     return 0;
38 }