思路：
最小循环节的解释在这里，有人证明了那么就很好计算了
之前对KMP了解不是很深啊，就很容易做错，特别是对fail的理解
代码：
#include<iostream>
#include<algorithm>
const int N = 1000000+5;
const int INF = 0x3f3f3f3f;
using namespace std;
int fail[N];
char p[N],t[N];
void getFail(){
fail[0] = -1;
int j = 0,k = -1;
int len = strlen(p);
while(j <= len){ //给等号
if(k == -1 || p[j] == p[k]){
if(p[++j] == p[++k])
fail[j] = fail[k];
else
fail[j] = k;
}
else{
k = fail[k];
}
}
}
int KMP(){
int num = 0;
getFail();
int i = 0,j = 0;
int lent = strlen(t),lenp = strlen(p);
while(i < lent){
if(j == -1 || t[i] == p[j]){
i++;
j++;
if(j == lenp) num++;
}
else{
j = fail[j];
}
}
return num;
}
int main(){
int T;
scanf("%d",&T);
while(T--){
scanf("%s",p);
getFail();
int len = strlen(p);
int c = len - fail[len]; //最小循环节
if(len % c == 0){
if(len == c) printf("%d\n",c);
else printf("0\n");
}
else{
printf("%d\n",c - len%c);
}
}
return 0;
}