int gcd(int a,int b){//求最大公约数    if(a==0||b==0)        return -1;    int t=a;    if(a<b)    {                a=b;        b=t;    }    while(b)    {      t=a%b;      a=b;      b=t;    }    return a;}void rotation(char *p,int n,int rotdist){//旋转    int right=gcd(rotdist,n);    for(int i=0;i<right;i++){        char t=p[i];        int j=i;        while(true){            int k=j+rotdist;            if(k>=n)                k-=n;            if(k==i)                break;            p[j]=p[k];            j=k;        }        p[j]=t;    }}