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;

}