题解 | #包含数字9的数#

#include <stdio.h>

int main() {
    int count = 0;
    for (int i = 1; i <= 2019; i++) {
        int a = i;
        while (a > 0) {
            if (a % 10 == 9) {
                count++;
                break;
            }
            a /= 10;
        }
    }
    printf("%d\n", count);
    return 0;
}