3046453_ce.c

来自「北大大牛代码 1240道题的原代码 超级权威」· C语言 代码 · 共 79 行

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

int sum(int num)
{
	int i, ret (0);
	char str[10];

	itoa(num,str,10);
	for(i = 0; str[i]; i++)
	{
		ret += str[i]-'0';
	}
	return ret;
}

int prime(int num)
{
	int i, t, tt, l, ret;

	if(num==2)
		return -1;
	tt = num;
	ret = 0;l = 0;
	if(num%2==0)
	{
		while(num%2==0)
		{
			num /= 2;
			l++;
		}
	}
	ret = l*2;
	t = sqrt(num);
	for(i = 3; i <= t; i+=2)
	{
		if(num%i==0)
		{
			l = 0;
			while(num%i==0)
			{
				l++;
				num /= i;
			}
			ret += l*sum(i);
			t = sqrt(num);
		}
	}
	if(num == tt)
		return -1;
	if(num!=1)
	{
		ret += sum(num);
	}
	return ret;
}

int main()
{
	int num;
	int a, b;

	while(scanf("%d",&num)==1,num)
	{
		while(1)
		{
			num++;
			a = sum(num);
			b = prime(num);
			if(a==b)
			{
				printf("%d\n",num);
				break;
			}
		}
	}
	return 0;
}