得到輸入，列出三種日期可能，判斷每種可能是否是正常日期；

對日期進行排序；

輸出不重複的正常日期。

#include<stdio.h>
#include<stdlib.h>
typedef struct
{
	int year,month,day,none;
}date;
date sp[4]={0};
int getday(int year)
{
	if((year%4==0&&year%100)||year%400==0)
		return 29;
	return 28;
}
void format(int year,int month,int day,int index)
{
	sp[index].none=0;
	if(year>=60)
		year+=1900;
	else
		year+=2000;
	sp[index].year=year;
	if(month>12||month<1)
	{
		sp[index].none=1;
		return;
	}
	sp[index].month=month;
	int daylist[13]={0,31,getday(year),31,30,31,30,31,31,30,31,30,31};
	if(day<1||day>daylist[month])
	{
		sp[index].none=1;
		return;
	}
	sp[index].day=day;
	return;
}
int compare(const void *a,const void *b)
{
	const date *sa=(const date*)a;
	const date *sb=(const date*)b;
	if(sa->year!=sb->year)
		return sa->year-sb->year;
	if(sa->month!=sb->month)
		return sa->month-sb->month;
	if(sa->day!=sb->day)
		return sa->day-sb->day;
	return 0;
}
int main(int argc,char **argv)
{
	int aa,bb,cc;
	scanf("%d/%d/%d",&aa,&bb,&cc);
	format(aa,bb,cc,1);
	format(cc,aa,bb,2);
	format(cc,bb,aa,3);
	qsort(sp+1,3,sizeof(date),compare);
	int i;
	date history={0};
	for(i=1;i<=3;i++)
		if(!sp[i].none&&compare(&history,&sp[i]))
		{
			history=sp[i];
			printf("%d-%02d-%02d\n",sp[i].year,sp[i].month,sp[i].day);
		}
	return EXIT_SUCCESS;
}
 

END