【KMP（循环节）】hdu 3746 Cyclic Nacklace

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

const int NM=100005;
int next[NM];
char str[NM];

void get_next(int len)
{
int i,j;
next[0]=-1;
j=-1;i=0;
while(i<len)  //最朴素的KMP
{
if(j==-1||str[i]==str[j])
{
i++;
j++;
next[i]=j;
}
else j=next[j];
}
}

int main()
{
int T,ans,len;
scanf("%d",&T);
while(T--)
{
scanf("%s",str);
len=strlen(str);
get_next(len);
ans=len-next[len];  //最小的循环节
if(ans!=len&&len%ans==0)
printf("0\n");
else
printf("%d\n",ans-len%ans);
}
return 0;
}