USACO of friday

/*
ID: jackson21
PROG: friday
LANG: C++
*/
#include <iostream>
#include <string>
#include <fstream>

using namespace std;
struct mdate;
bool judge_leap_year(const mdate date);

struct mdate
{
unsigned short year;
unsigned char month;
unsigned char day;
unsigned char week;


};

void increase(mdate& date)
{
date.week = (date.week)%7 + 1;
switch (date.month)
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
{
// 处理当天数增加时的影响
if ( date.day == 31 )
{
date.day = 1;
if(date.month == 12)
{
date.month = 1;
date.year++;
}
else
date.month++;
}
else
{
date.day++;
}
}
break;
case 4:
case 6:
case 9:
case 11:
{
// 处理每个月30天的情况
if ( date.day == 30 )
{
date.day = 1;
date.month++;
}
else
{
date.day++;
}
}
break;
case 2:
{
// first judge whether it is leap year
if ( date.day < 28 )
{
date.day++;
}
else if ( date.day == 28 )
{
if (!judge_leap_year(date))
{
date.month++;
date.day = 1;
}
else
date.day++;
}
else
{
date.day = 1;
date.month++;
}
}
}
}

// void PrintDate(const mdate date)
// {
// cout << (int)date.year <<"/"<< (int)date.month << "/" << (int)date.day <<" is WEEK " << (int)date.week << endl;
// }

int main()
{
// entry point
// get input number of year
unsigned short counter[8] = {0}; // 1 - 7 stands for Monday to Sunday 
ifstream fin;
ofstream fout;
unsigned short years = 0;
fin.open("friday.in");
fout.open("friday.out");
fin >> years;

mdate original = {1900, 1, 1, 1};
while(original.year <= (1900 + years - 1))
{
increase(original);
if ( original.day == 13 )
{
counter[original.week]++;
}
}

fout << counter[6] << " "<< counter[7] << " "<< counter[1] << " "<< counter[2] << " "
<< counter[3] << " "<< counter[4] << " "<< counter[5] << endl;

return 0;
}

bool judge_leap_year(mdate date)
{
if( date.year % 400 == 0 )
return true;
if( date.year % 4 == 0 )
{
if (date.year % 100 == 0)
return false;
else
return true;
}
else
{
return false;
}
}