算法--第二次作业

第一题:

import java.util.Scanner;

public class RSA {

public static void main(String[] args) {

// TODO Auto-generated method stub

System.out.println("请输入一个数:");

Scanner s1=new Scanner(System.in);

int i=s1.nextInt();

boolean a=false;

for(int j=2;j<i;j++){

if(i%j==0){

a=true;

break;

}

}

if(a){

System.out.print("该数不是质数");

}else System.out.print("该数为一个质数");

}

}

第二题:

import java.util.Random;

import java.util.Scanner;

public class RSA {

public static void main(String[] args) {

System.out.print("请输入所要生成数的长度:");

Scanner s=new Scanner(System.in);

int i=s.nextInt();

System.out.print(createRanInteger(i));

}

public static long createRanInteger(int n){

int []a={0,1};

StringBuilder s=new StringBuilder();

Random r=new Random();

s.append(1);

for(int j=0;j<n;j++){

s.append(a[r.nextInt(a.length)]);

}

System.out.println(s);

long num=Long.parseLong(s.toString(),2);

return num;

}

}