POJ 2406Power Strings(KMP)

POJ 2406

其实就是一个简单的kmp应用：

ans = n % (n - f[n]) == 0 ? n / (n - f[n]) : 1

其中f是失配函数

 //#pragma comment(linker, "/STACK:1677721600")
 #include <map>
 #include <set>
 #include <stack>
 #include <queue>
 #include <cmath>
 #include <ctime>
 #include <vector>
 #include <cstdio>
 #include <cctype>
 #include <cstring>
 #include <cstdlib>
 #include <iostream>
 #include <algorithm>
 using namespace std;
 #define INF 0x3f3f3f3f
 #define inf (-((LL)1<<40))
 #define lson k<<1, L, (L + R)>>1
 #define rson k<<1|1,  ((L + R)>>1) + 1, R
 #define mem0(a) memset(a,0,sizeof(a))
 #define mem1(a) memset(a,-1,sizeof(a))
 #define mem(a, b) memset(a, b, sizeof(a))
 #define FIN freopen("in.txt", "r", stdin)
 #define FOUT freopen("out.txt", "w", stdout)
 #define rep(i, a, b) for(int i = a; i <= b; i ++)
 #define dec(i, a, b) for(int i = a; i >= b; i --)

 template<class T> T MAX(T a, T b) { return a > b ? a : b; }
 template<class T> T MIN(T a, T b) { return a < b ? a : b; }
 template<class T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; }
 template<class T> T LCM(T a, T b) { return a / GCD(a,b) * b;    }

 //typedef __int64 LL;
 typedef long long LL;
 const int MAXN =  + ;
 const int MAXM = ;
 const double eps = 1e-;
 LL MOD = ;

 char s[MAXN];
 int f[MAXN];

 void get_next(int n) {
     mem0(f);
     rep (i, , n - ) {
         int j = f[i];
         while(j && s[i] != s[j])  j = f[j];
         f[i + ] = s[i] == s[j] ? j +  : ;
     }
 }

 int main()
 {
     //FIN;
     while(~scanf("%s", s) && s[] != '.') {
         int n = strlen(s);
         get_next(n);
         printf("%d\n", n % (n - f[n]) ==  ? n / (n - f[n]) : );
     }
     return ;
 }