UVA 12290 Counting Game

http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=23582

题目挂了

n个人中的m号  喊第k次的数字是多少

#include <cstdio>using namespace std;int pd(int n){    if(n%7==0)return 1;    while(n)    {        if(n%10==7)return 1;        n/=10;    }    return 0;}int main(){    int m,n,k,a,b;    while(scanf("%d%d%d",&m,&n,&k)!=EOF)    {        if(m==0&&n==0&&k==0)break;        if(k==1&&pd(n)){printf("%d\n",n);continue;}        a=n;        if(pd(a))k--;        while(k>=1)        {            b=a;            a+=(m-n)*2;            if(a!=b&&pd(a)){if(k==1){printf("%d\n",a);break;}else k--;}            b=a;            a+=(n-1)*2;            if(a!=b&&pd(a)){if(k==1){printf("%d\n",a);break;}else k--;}        }        if(k==0)printf("-1\n");    }    return 0;}