题解 | #[NOIP2010]数字统计#

知识点：

函数：函数

#include <iostream>
using namespace std;

int fun(int l, int r);

int main() {
    int l, r;
    int count_2;
    cin >> l >> r;

    count_2 = fun(l, r);

    cout << count_2;

    return 0;
}

int fun(int l, int r) {
    int sum = 0;
    int temp;
    int n;

    for (int i = l; i <= r; i++) {
        n = i;

        while (n > 0) {
            temp = n % 10;

            if (temp == 2) {
                sum++;
            }

            n /= 10;
        }
    }

    return sum;
}

/*
int fun(int n);

int main() {
    int l, r;
    int sum = 0;
    cin >> l >> r;

    for (int i = l; i <= r; i++) {
        sum += fun(i);
    }

    cout << sum;

    return 0;
}

int fun(int n) {
    int sum = 0;
    int temp;

    while (n > 0) {
        temp = n % 10;
        if (temp == 2) {
            sum++;
        }
        n /= 10;
    }

    return sum;
}
*/