每日一题洛谷B2136 素数回文数的个数c++

 

#include
using namespace std;
int main() {
	int n;
	cin >> n;
	int c = 0;
	for (int i = 11; i <= n; i++) {
		int t = i;
		int sum = 0;
		while (t) {
			sum = sum * 10 + t % 10;
			t /= 10;
		}
		if (sum == i) {
			int flag = 1;
			for (int j = 2; j * j <= i; j++) {
				if (i % j == 0) {
					flag = 0;
					break;
				}
			}
			if (flag)c++;
		}
	}
	cout << c << endl;
	return 0;
}