题解 | 质数因子

#include <iostream>
#include <vector>
using namespace std;

bool isprime(int k) {  //judge number is prime or not
    for (int i = 2; i * i <= k; ++i) {
        if (k % i == 0)
            return false;
    }
    return true;
}

int main() {
    int n;
    while (cin >> n) {
        int half = n/2;
        vector<int> arr; //arr store prime factor
        for (int i = 2; i <= half; ++i) {
            if (isprime(n)) {
                arr.push_back(n);
                break;
            } else {
                if ( n % i == 0) {
                    arr.push_back(i); //add prime factor
                    n = n / i;
                    i = 1;
                }
            }
        }
        for (int k : arr) {
            cout << k << " ";
        }
    }
    return 0;
}