zoj 2934 Persistent Bits

#include <cstdio>#include <cstring>int vis[1000000];int main(){    int str[47];    int a, b, c, s;    while(scanf("%d",&a))    {        if(a == 0) break;        scanf("%d%d%d",&b,&c,&s);        memset(vis,0,sizeof(vis));        int tt = s;        int l = 0;        while(tt)        { str[l++] = tt%2; tt/=2;        }        for(int i = l; l < 16; l++)        { str[i++] = 0;        }        tt = s;        while(!vis[tt])        { l = 0; vis[tt] = 1; int tm = tt; while(tm) {     if(str[l] != tm%2)     {         str[l] = 3;     }     tm/=2;     l++; } tt = (((a*tt)%c) + (b%c))%c ;        }        for(int i = 15; i >= 0; i--)        { if(str[i]!=3)     printf("%d",str[i]); else     printf("?");        }        printf("n");    }    return 0;}