POJ1961 Period

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 
 7 inline void read(int &x)
 8 {
 9     x = 0;char ch = getchar(), c = ch;
10     while(ch < ‘0‘ || ch > ‘9‘)c = ch, ch = getchar();
11     while(ch <= ‘9‘ && ch >= ‘0‘)x = x * 10 + ch - ‘0‘, ch = getchar();
12     if(c == ‘-‘)x = -x;
13 }
14 
15 const int MAXN = 2000000 + 10;
16 
17 char s[MAXN];
18 int n,lens,next[MAXN];
19 
20 void make_next()
21 {
22     memset(next, 0, sizeof(next));
23     next[0] = -1;
24     for(int i = 1, j = -1; i < lens; ++ i)
25     {
26         while(j >= 0 && s[j+1] != s[i]) j = next[j];
27         if(s[j+1] == s[i]) ++ j;
28         next[i] = j;
29     }
30     for(register int i = 0;i < lens;++ i) ++next[i];
31 }
32 
33 int cnt;
34 
35 int main()
36 {
37     while(scanf("%d", &lens) != EOF && lens)
38     {
39         ++cnt;
40         scanf("%s", s);
41         printf("Test case #%d\n", cnt);
42         make_next();register int lenp;
43         for(register int i = 2;i <= lens;++ i)
44         {
45             lenp = next[i - 1];
46             if((lenp << 1) >= i && i % (i - lenp) == 0)
47                 printf("%d %d\n", i, i/(i - lenp));
48         }
49         putchar(‘\n‘);
50     }
51     return 0;
52 ;}