C语言解答

#include<stdio.h>
int prime(int n)
{
	int i;
	for(i=2;i*i<=n;i++)
	{
		if(n%i==0)break;
	}
	if(i*i<=n)
		return 0;
	else
		return 1;
}
int main()
{
	int n;
	scanf("%d",&n);
	if(prime(n))
		printf("prime\n");
	else
		printf("not prime\n");
	return 0;
}

C++解答

#include <stdio.h>
#include <math.h>
int main() {
	int isprime(int x);
	int i, m;
	scanf("%d", &m);
	if (isprime(m) == 1)
		printf("prime\n");
	else
		printf("not prime\n");
	return 0;
}
int isprime(int x) {
	int prime = 1, i;
	for (i = 2;i * i <= x;i++) {
		if (x % i == 0) {
			prime = 0;
			break;
		}
	}
	return prime;
}

Java解答

import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner in=new Scanner(System.in);
		int n=in.nextInt();
		boolean is=true;
		for(int d=2;d<=n/2;d++){
			if(n%d==0){
				is=false;
				break;
			}
		}
		if(is)
			System.out.println ("prime");
		else
			System.out.println ("not prime");
	}	
}