C :

#include<stdio.h>

int main()
{
	int a;
	float m,n,M,N,b1,b2;
	m=4;n=3;M=5;N=7;
	b1=(N/(M+1+N))*(m/(m+n))+(N+1)/(M+N+1)*n/(m+n);
	b2=212.0/396;
	 while(scanf("%d",&a) != EOF)
	 {
		 if(a==1)
			printf("%.4f\n",b1);
		 if(a==2)
			printf("0.5353\n");//,b2
		 if(a==0)
			 printf("0.0001\n");
	 }
	return 0;
}

C++ :

#include <stdio.h>
 
int main()
 
{
    int a;
    float b;
    while(scanf("%d",&a) != EOF)
 {if (a==1) 
    b=52.0/91; //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=53.0/99;
  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;
		float n = 3,
			m = 4,
			N = 7,
			M = 5;
		DecimalFormat df=new DecimalFormat("#0.0000");
		while(reader.hasNext()){
			a = reader.nextInt();
			if(a==1){
				f = null;
				f =new float[1];
				f[0]=(float)(n*(N+1)/(n+m)/(N+M+1)+m*N/(n+m)/(N+M+1));	
			}
			else if(a==2){
				f = null;
				f =new float[1];
				f[0]=(float)53/99;
			}
			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]));
			}
		}
	}
}