思路：

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
    
     #include
     
      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;}