题解 | #[NOIP2010]数字统计#

#include<stdio.h>
int count2(int i)
{
	int count = 0;
	while (i!=0)
	{
		if (i % 10 == 2)   
			count++;
		i = i / 10;
	}
	return count;

}

int main()
{
	int L, R,sum=0;
	scanf("%d %d", &L, &R);

	for (int i = L; i <= R; i++)
	{
		sum += count2(i);  //将每次i得到的count累加起来
	}

	printf("%d", sum);
	return 0;
}