Power Strings POJ - 2406

 1 //#include <bits/stdc++.h>
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <cstring>
 5 #include <algorithm>
 6 using namespace std;
 7 const int maxn = 1000010;
 8 char s[maxn];
 9 int sa[maxn], t1[maxn], t2[maxn], c[maxn];
10 int h[maxn], rk[maxn];
11 int n;
12 void build_sa(int n, int m){
13     int i, *x = t1, *y = t2;
14     for(i = 0; i < m; i++) c[i] = 0;
15     for(i = 0; i < n; i++) c[x[i] = s[i]]++;
16     for(i = 1; i < m; i++) c[i] += c[i-1];
17     for(i = n-1; i >= 0; i--) sa[--c[x[i]]] = i;
18     for(int k = 1; k <= n; k <<= 1){
19         int p = 0;
20         for(i = n-k; i < n; i++) y[p++] = i;
21         for(i = 0; i < n; i++) if(sa[i] >= k) y[p++] = sa[i]-k; 
22         for(i = 0; i < m; i++) c[i] = 0;
23         for(i = 0; i < n; i++) c[x[y[i]]]++;
24         for(i = 1; i< m; i++) c[i] += c[i-1];
25         for(i = n-1; i >= 0; i--) sa[--c[x[y[i]]]] = y[i];
26         swap(x,y);
27         p = 1;
28         x[sa[0]] = 0;
29         for(i = 1; i < n; i++) 
30           x[sa[i]] = y[sa[i]]==y[sa[i-1]] && y[sa[i]+k]==y[sa[i-1]+k]? p-1 : p++;
31         if(p>=n) break;
32         m=p;
33     }
34 }
35 void geth(int n){
36     int i, j, k=0;
37     for(i = 0; i < n; i++) rk[sa[i]]=i; 
38     for(i = 0; i < n; i++) {
39         if(k) k--;
40         j = sa[rk[i]-1];
41         while(s[i+k]==s[j+k]) k++;
42         h[rk[i]] = k;
43     }
44 }
45 int main(){
46     while(scanf("%s", s)){
47         if(s[0] == ‘.‘) break;
48         int n = strlen(s) + 1;  //!!!
49         build_sa(n, 255);
50         geth(n);
51         int k;
52         n--;
53         for(k = 1; k <= n; k++){
54             if(n%k==0 && h[rk[0]] == n-k) break;
55         }
56         printf("%d\n", n/k);
57     }
58 }