C :

#include <stdio.h>
 
int main()
 
{
    int a;
float b[2];
    while(scanf("%d",&a) != EOF)
 {
 if (a==1) 
   b[0]=4.0/33;
  else if(a==2)
    b[0]=10.0/33;
  else if(a==0)
		b[0]=0.0001;
        printf("%.4f\n",b[0]);
		
}
    return 0;
}

C++ :

#include <stdio.h>
 
int main()
 
{
    int a;
    float b;
    while(scanf("%d",&a) != EOF)
 {if (a==1) 
    b=4.0/33; //将“作业答案”替换为该题答案。若有多行，用多行重复输出。
  else if (a==2)
    b=10.0/33;
  else 
	b=0.0001;
        printf("%.4f\n",b);
}
    return 0;
}

Java :

import java.text.DecimalFormat;
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		
		float f[] = new float[2];
		Scanner reader = new Scanner(System.in); 
		int a;
		DecimalFormat df=new DecimalFormat("#0.0000");
		while(reader.hasNext()){
			a = reader.nextInt();
			if(a==1){
				f = null;
				f =new float[1];
				f[0]=(float)60/495;
				
				
				
			}
			else if(a==2){
				f = null;
				f =new float[1];
				f[0]=(float)240/792;
			}
			else {
				f = null;
				f =new float[1];
				f[0] = (float) 0.0001;
			}
			for(int i=0;i<f.length;i++){
				
				System.out.println(df.format(f[i]));
			}
		}
	}
}