请问为什么这样运行结果正确，但无法通过？

#include <stdio.h>

int main() 

{ 

    /* 定义需要计算的日期 */

    int year = 2008;

    int month = 8;

    int day = 8;

    int sum;

    switch (month)

    {

        case 1 : sum = 0+day;break;

        case 2 : sum = 31+day;break;

        case 3 : sum = 31+28+day;break;

        case 4 : sum = 31+28+31+day;break;

        case 5 : sum = 31+28+31+30+day;break;

        case 6 : sum = 31+28+31+30+31+day;break;

        case 7 : sum = 31+28+31+30+31+30+day;break;

        case 8 : sum = 31+28+31+30+31+30+31+day;break;

        case 9 : sum = 31+28+31+30+31+30+31+31+day;break;

        case 10 : sum = 31+28+31+30+31+30+31+31+30+day;break;

        case 11 : sum = 31+28+31+30+31+30+31+31+30+31+day;break;

        case 12 : sum = 31+28+31+30+31+30+31+31+30+31+30+day;break;

    }

    if ((year%4==0&&year%100!=0) || year%400==0)

        {

            if (month>2)

                printf ("%d",sum+1);

            else

                printf ("%d",sum);

        }

    else 

        printf ("%d",sum);

return 0;

}