Naive unlucky numbers generator

#include <cstdio>
#include <vector>

using namespace std;

constexpr int N = 1000000000;

/* Returns true if n is an unlucky number. */
bool check(int n) {
    int sum, last, cur;
    bool has;

    sum = 0;
    last = -1;
    has = false;

    while (n > 0) {
        cur = n % 10; // Current digit.
        n /= 10;

        if (cur == 1 and last == 3) { // Checking if has 13 as a substring.
            has = true;
        }

        sum += cur; // Updating sum.
        last = cur; // Updating last digit.
    }

    return has and sum == 13; // Valid if has 13 as a substring and sum is 13.
}

int main() {
    vector<int> ans;

    // Generating all the unlucky numbers.
    for (int n = 1; n <= N; n++) {
        if (check(n)) {
            ans.push_back(n);
        }
    }

    // Printing all the unlucky numbers in ascending order as a vector declaration.
    printf("vector<int> ans = {");

    for (int i = 0; i < ans.size() - 1; i++) {
        printf("%d, ", ans[i]);
    }

    printf("%d};\n", ans.back());

    return 0;
}