poj 1597 Uniform Generator

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>using namespace std;#define maxn 100005int step, mod;bool vis[maxn];int generate(int step, int mod){    memset(vis, 0, sizeof(vis));    int x = 0;    int ret = 0;    while (!vis[x])    {        vis[x] = true;        x = (x + step) % mod;        ret++;    }    return ret;}int main(){    while (~scanf("%d%d", &step, &mod))    {        if (generate(step, mod) == mod) printf("%10d%10d    Good Choicen", step, mod);        else printf("%10d%10d    Bad Choicen", step, mod);        puts("");    }    return 0;}