题目描述

进制转化+质数判断

C++ 代码

#include <iostream>
#include <algorithm>
using namespace std;
vector<int> to_d(int n, int d)
{
    vector<int> ans;
    do ans.push_back(n % d), n /= d; while (n);
    return ans;
}
int to_10(vector<int> n, int d)
{
    int t = 1, ans = 0;
    for (int i = n.size() - 1; i >= 0; i --)
        ans += n[i] * t, t *= d;
    return ans;
}
bool is_prime(int n)
{
    if (n <= 1) return false;
    for (int i = 2; i <= n / i; i ++)
        if (n % i == 0) return false;
    return true;
}
int main()
{
    int n, d;
    while (true)
    {
        cin >> n;
        if (n < 0) break;
        cin >> d;
        vector<int> v = to_d(n, d);
        n = to_10(v, d);
        if (is_prime(n)) puts("Yes");
        else puts("No");
    }
}