从2000年一月一日算，给一个天数，算出它是多少年月日 星期几

/#include <iostream> 
#include <string> 
using namespace std; 
bool isLeapYear(int year)                            //判断是否为闰年
 {
return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
 }

 int main()
 { 
string week[] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};         //定义字符串数组存储星期
int monthDay[] = {0, 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};     //定义整型数组保存每月的天数
int leapYear[] = {365, 366};   //定义整型数组保存每年的天数
int year;
int month; 
int day; 
int d; 
int dayofweek;
while(cin>>d && d != -1)
{ 
//从2000-01-01开始计算
year = 2000; 
month = 1;
day = 1; 
dayofweek = 6;
while(d >= leapYear[isLeapYear(year)])    //处理每一年  
{ 
dayofweek = (dayofweek + leapYear[isLeapYear(year)]%7) % 7;
d -= leapYear[isLeapYear(year)];
year++; 
} 
for(int i=1; i<=d; i++) 
{ 
dayofweek++; 
if(dayofweek % 7 == 0) //星期，七天一个周期循环 
{ 
dayofweek = 0;
} 
day++; 
if(month != 2 && day > monthDay[month]) //到了一个月的最后一天，月份累加 
{
month++; day = 1; 
}
if(month == 2 && isLeapYear(year) && day > 29)// 二月份单独算
{ 
month++; 
day = 1; 
} 
if(month == 2 && !isLeapYear(year) && day > 28) 
{ 
month++; 
day = 1; 
} 
if(month > 12) //到了12月，年累加
{
month = 1; 
year++; 
}
}
cout<<year<<"-"; 
if(month<10) 
{ 
cout<<"0"<<month; 
} 
else 
{ 
cout<<month;
}
cout<<"-"; 
if(day<10) 
{ cout<<"0"<<day; 
} 
else 
{ 
cout<<day;
} 
cout<<" "<<week[dayofweek]<<endl; 
} 
return 0; 
 }