Uva--10392 (数学)

2014-06-12 01:11:10

题意＆思路：素数拆分，注意一下中间判素数直接输出而防止超时。

#include <cstdio>
#include <cmath>
#include <iostream>
using namespace std;

bool isprime(long long x){
    for(long long i = 2; i * i <= x; ++i){
        if(x % i == 0)
            return false;
    }
    return true;
}

int main(){
    long long num;
    while(scanf("%lld",&num) == 1){
        if(num <0 )
            break;
        if(isprime(num)){
            printf("    %lld\n\n",num);
            continue;
        }
        int flag = 0;
        for(long long i = 2; num != 1; ++i){
            while(num % i == 0){
                printf("    %lld\n",i);
                num /= i;
                if(num != 1 && isprime(num)){
                    printf("    %lld\n",num);
                    flag = 1;
                    break;
                }
            }
            if(flag) break;
        }
        puts("");
    }
    return 0;
}