题解 | #[NOIP2010]数字统计#

#include <stdio.h>
int two(int l, int r)
{
    int cnt = 0;
    for (int i = l; i <= r; i++)
    {
        int temp = i;//暂时存储i的值
        while (temp)
        {
            if (temp % 10 == 2)
            {
                cnt++;
            }
            temp /= 10;
        }
    }
    return cnt;
}
int main() 
{
    int l = 0;
    int r = 0;
    while (~scanf("%d %d", &l, &r))
    {
        //统计数字2出现的次数
        int cnt = two(l, r);
        
        //输出
        printf("%d\n", cnt);
    }
    return 0;
}