POJ 2406 Power Strings

用KMP求循环节。

/*Accepted    5288K    110MS    G++    712B    2012-08-01 16:03:19*/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>

const int MAXN = 1 << 20;
char t[MAXN];
int next[MAXN], len;

void Make_Next()
{
    int i = 0, j = -1;
    next[0] = -1;
    len = strlen(t);
    while(i < len)
    {
        if(-1 == j || t[i] == t[j])
        {
            ++ i, ++ j;
            if(t[i] != t[j]) next[i] = j;
            else next[i] = next[j];
        }
        else
            j = next[j];
    }
}

int cal()
{
    if(len % (len - next[len]) == 0)
        return len / (len - next[len]);
    return 1;
}

int main()
{
    while(scanf("%s", t) && t[0] != '.')
    {
        Make_Next();
        printf("%d\n", cal());
    }
    return 0;
}