题解 | #素数#

#include <iostream>
#include<math.h>
using namespace std;
//求素数
bool SuNum(int x) {
    bool tag0 = true;
    if (x == 2 || x == 3) {
        return true;
    }
    for (int i = 2; i <= (int)sqrt(x); i++) {
        if (x % i == 0) {
            tag0 = false;
        }
    }
    return tag0;
}
//判定个位是否为1
bool isOne(int x) {
    if (x % 10 == 1) return true;
    return false;
}
int main() {
    int x, tag = -1;
    while (scanf("%d", &x) != EOF) {
        for (int i = 2; i < x; i++) {
            if (SuNum(i) && isOne(i)) {
                cout << i << " ";
                tag = 0;
            }
        }
        if (tag == -1) cout << tag;
    }
    return 0;
}