#include <stdio.h>
void Monthhead(int month)
{

	printf("%s\n",(month==1)?"Jan":(month==2)?"Feb":(month==3)?"Mar":(month==4)?"Apr":(month==5)?"May":(month==6)?"Jun":(month==7)?"Jul":(month==8)?"Aug":(month==9)?"Sep":(month==10)?"Oct":(month==11)?"Nov":"Dec");
    return;
}
void dayHead()
{
	printf(" Sun Mon Tue Med Thu Fri Sat\n");
	return;
}
int firstDay(int year)
{
	int b=(year-1)*365+(year-1)*400+(year-1)*4-(year-1)*100+1;
	return b%7;
}
int Week6(int year,int month)
{
	int w,c,y;
    int day=1;
	if(month<3)
	{
		month+=12;
		year--;
	}
	c=year/100;
	y=year%100;
	w=(c/4-2*c+y+y/4+13*(month+1)/5+day-1)%7;
	return w;
}
int Week(int year,int month,int day)
{
	int w,c,y;
	if(year<=1582&&month<=10&&day<15)
	{
	if(month<3)
	{
		month+=12;
		year--;
	}
	day-=4;
	c=year/100;
	y=year%100;
	w=(c/4-2*c+y+y/4+13*(month+1)/5+day-1)%7;
	}else{
		if(month<3)
			{
				month+=12;
				year--;
			}
			c=year/100;
			y=year%100;
			w=(c/4-2*c+y+y/4+13*(month+1)/5+day-1)%7;
	}
	
	return w;
}
int isLeapYear(int year)
{
return (year%4==0&&year%100!=0)||year%400==0;
	
}
int DayMonth(int year,int month)
{

		if(month==2)
		{
			if(isLeapYear(year))
			{
				return 29;
			}else{
				return 28;
			}
		}else if(month==4||month==6||month==9||month==11){
			return 30;
		}else{
			return 31;
		}
}
void printCalendar3(int year)
{
	int first=firstDay(year);
	int month,day;
	for(month=1;month<=9;month++)
	{
		printf("\n");
	Monthhead(month);
	dayHead();
	for(day=1;day<=first;day++)
	printf("    ");
	int dayMonth=DayMonth(year,month);
	   for(day=1;day<=dayMonth;day++)
	   {
		printf("%4d",day);
		if((day+first)%7==0)
		{
			printf("\n");
		}
       }
       	if((day+first)%7!=0)
	   		{
	   			printf("\n");
	   		}
       first=(first+dayMonth)%7;
	}
	for(month=10;month<=12;month++)
	{
		int i;
		
		
		day=1;
		if(month==10)
		{
			int a[21]={1,2,3,4,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31};
			Monthhead(month);
			dayHead();
		
			int first2=Week(year,month,day);
			for(i=1;i<=first2;i++)
			printf("    ");
			for(i=0;i<21;i++)
			{
				printf("%4d",a[i]);
				if((i+first2+1)%7==0)
						{
							printf("\n");
						}
			}
			if((i+first2)%7!=0)
				   		{
				   			printf("\n");
				   		}
			       first2=(first2+21)%7;
			       continue;
		}
		printf("\n");
int first3=Week(year,month,day);
	Monthhead(month);
	dayHead();
	for(i=1;i<=first3;i++)
	printf("    ");
	int dayMonth;
	if(month==11){
	dayMonth=30;
	}else if(month==12){
			dayMonth=31;
	}
	   for(i=1;i<=dayMonth;i++)
	   {
		printf("%4d",i);
		if((i+first3)%7==0)
		{
			printf("\n");
		}
       }
       	if((i+first3)%7!=0)
	   		{
	   			printf("\n");
	   		}
       first3=(first3+dayMonth)%7;

		
	}
	printf("\n");
}
void printCalendar(int year)
{
	int first=firstDay(year);
	int month,day;
	for(month=1;month<=12;month++)
	{
	Monthhead(month);
	dayHead();
	for(day=1;day<=first;day++)
	printf("    ");
	int dayMonth=DayMonth(year,month);
	   for(day=1;day<=dayMonth;day++)
	   {
		printf("%4d",day);
		if((day+first)%7==0)
		{
			printf("\n");
		}
       }
       	if((day+first)%7!=0)
	   		{
	   			printf("\n");
	   		}
       first=(first+dayMonth)%7;
	}
}
long int f(int year,int month)

{

if(month<3) return year-1;

else return year;

}

long int g(int month)

{

if(month<3) return month+13;

else return month+1;

}

long int n(int year,int month,int day)

{

return 1461L*f(year,month)/4+153L*g(month)/5+day;

}

int w(int year,int month,int day)

{

return(int) ((n(year,month,day)%7-621049L%7+7)%7);

}

int date[12][6][7];

int day_tbl[ ][12]={{31,28,31,30,31,30,31,31,30,31,30,31},{31,29,31,30,31,30,31,31,30,31,30,31}};

int Double(int year)
{

int sw,leap,i,j,k,wd,day;

char title[]="SUM  MON  TUE  WED  THU  FRI  SAT";

sw=w(year,1,1);

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

for(i=0;i<12;i++)

for(j=0;j<6;j++)

for(k=0;k<7;k++)

date[i][j][k]=0;

for(i=0;i<12;i++)

for(wd=0,day=1;day<=day_tbl[leap][i];day++)

{

date[i][wd][sw]=day;

sw=++sw%7;
if(sw==0) wd++;

}

printf("\n================== The Calendar of Year %d==================\n",year);

for(i=0;i<6;i++)

{

for(wd=0,k=0;k<7;k++)

wd+=date[i][5][k]+date[i+6][5][k];

wd=wd?6:5;

printf("%2d %s    %2d %s\n",i+1,title,i+7,title);

for(j=0;j<6;j++)
{

/*printf("     ");*/

for(k=0;k<7;k++)

if(date[i][j][k])

printf("%5d",date[i][j][k]);

else printf("     ");

printf("     ");


for(k=0;k<7;k++)

if(date[i+6][j][k])

printf("%5d",date[i+6][j][k]);

else printf("     ");

printf("\n");

}
}
}


void choiceCalendar(int year)
{
	
	int choose;
	while(1){printf("1.单列\n2.双列\n");
	scanf("%d",&choose);
	switch(choose){
		case 1: if(year!=1582)
		{
			printCalendar(year);
		}else if(year==1582){
			printCalendar3(year);
		}
		break;
		case 2:Double(year);
		break;
		default:
			printf("输入有错误\n");
			break;
	}break;
}
}

int main()
{
	int choice,year,month,day;
	while(1)
	{
		printf("1.某年日历\n2.星期几\n3.闰年判断\n4.退出程序\n");
		printf("选哪个!\n");
		scanf("%d",&choice);
		switch(choice){
			case 1:printf("输入年份:\n");
			scanf("%d",&year);
			choiceCalendar(year);
			break;
			case 2:printf("输入某年某月某日(空格隔开):\n");
			scanf("%d %d %d",&year,&month,&day);
			int w=Week(year,month,day);
			printf("%d\n",w);
			break;
			case 3:printf("输入年份:\n");
						scanf("%d",&year);
						if(isLeapYear(year)){
							printf("YES\n");
						}else{
							printf("NO\n");
						}
						break;
			case 4:	return 0;
			        break;
			default:printf("无效选择\n");
			break;
				
		}
	}
	return 0;
	
}