1015 Reversible Primes

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#include <bits/stdc++.h>
using namespace std;

bool isPrime(int n) {
    if (n <= 1) return false; // 1不是素数
    int sqr = (int)sqrt(1.0 * n);
    for (int i = 2; i <= sqr; i++)
        if (n % i == 0) return false;
    return true;
}

int reverseN(int n, int d) {
    int arr[100] = {0}, len = 0;
    while (n) {
        arr[len++] = n % d;
        n /= d;
    }
    int res = 0;
    for (int i = 0; i < len; i++) {
        res = res * d + arr[i];
    }
    return res;
}

int main() {
    int n, d;
    while (scanf("%d", &n) != EOF && n > 0) {
        scanf("%d", &d);
        if (!isPrime(n)) {
            printf("No\n");
            continue;
        }
        n = reverseN(n, d);
        printf("%s", isPrime(n) ? "Yes\n" : "No\n");
    }

    return 0;
}


73 10
23 2
23 10
-2

Yes
Yes
No