C :

#include<stdio.h>
int main( int argc, char ** argv )
{
	int Step, Mod;
	while( scanf( "%d%d", &Step, &Mod ) != EOF )
	{
		int Book[100001] = { 0 };
		int Count = 0, S = 0;
		while( Book[S] == 0 )
		{
			Book[S] = 1;
			S = ( S + Step) % Mod;
			Count++;
		}
		if( Count == Mod )
			printf( "%10d%10d    Good Choice\n", Step, Mod );
		else
			printf( "%10d%10d    Bad Choice\n", Step, Mod );
	}
	return 0;
}

C++ :

#include<stdio.h>
#include<iostream>
#include<string.h>
using namespace std;
int f[100000];

int main()
{
	int  step, mod; // step，mod
	int  i, a;
	bool tag;

	while (cin >> step >> mod)
	{
		memset(f, 0, sizeof(f));
		tag = true;
		a = 0;
		f[a]++;

		for (i = 1; i < mod; i++)
		{
			a = (a + step) % mod;
			f[a]++;
			if (f[a] >= 2)
			{
				tag = false;
				break;
			}
		}

		printf("%10d%10d    ", step, mod); // 打印10位数

		if (tag)
			cout << "Good Choice" << endl;
		else
			cout << "Bad Choice" << endl;
	}
	
	return 0;
}

Java :

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Scanner;

public class Main{
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNext()){
			int step =in.nextInt();
			int mod =in.nextInt();
			boolean[] flag = new boolean[mod];
			Arrays.fill(flag, false);
			int step1 = 1;
			boolean B = true;
			for(int i=0;i<mod;i++){
				step1 =(step1+step)%mod;
				if(flag[step1]==false)
					flag[step1] = true;
				else{
					B=false;
					break;
				}					
			}
			if(B == false){
				System.out.printf("%10d%10d",step,mod);
				System.out.println("    "+"Bad Choice");
			}
			else{
				System.out.printf("%10d%10d",step,mod);
				System.out.println("    "+"Good Choice");
			}
				
		}
	}
}