解题思路：此题我想到俩种方法，一种是排序方法，一种是不排序的方法，首先都是看是否是有效年龄，然后一种是排序，另一种是维护最大值和最小值的变量，一定要注意如果有效数字是0那就只输出0就可以了。

c语言解法一：排序法

#include<stdio.h>
typedef struct
{
	char name[6];
	int year;
	int month;
	int day;
}old_man;
int valid(old_man m)
{
	if(m.year>2014||m.year<2014-200)
	return 0;
	if(m.year==2014&&(m.month>9||(m.month==9&&m.day>6)))
	{
		return 0;
		
	}
	if(m.year==2014-200&&(m.month<9||(m.month==9&&m.day<6)))
	return 0;
	return 1;	
}
int compare(old_man a,old_man b)
{
	if(a.year!=b.year)
	return b.year-a.year;
	if(a.month!=b.month)
	return b.month-a.month;
	return b.day-a.day;
}
int main()
{
	int n,youxiao=0,i;
	old_man max,min,current,temp;
	max.day=31,max.year=2015,max.month=12;
	min.day=0,min.year=0,min.month=0;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%s %d/%d/%d",current.name,&(current.year),&(current.month),&(current.day));
		if(valid(current))
		youxiao++;
		else
		continue;
		if(compare(max,current)<0)
		{
			max=current;
		}
		if(compare(current,min)<0)
		{
			min=current;
		}
	}
	if(youxiao)
	printf("%d %s %s\n",youxiao,max.name,min.name);
	else
	printf("%d\n",youxiao);
	return 0;
}

c语言解法二不排序：

#include<stdio.h>
typedef struct
{
	char name[6];
	int year;
	int month;
	int day;
}old_man;
int valid(old_man m)
{
	if(m.year>2014||m.year<2014-200)
	return 0;
	if(m.year==2014&&(m.month>9||(m.month==9&&m.day>6)))
	{
		return 0;
		
	}
	if(m.year==2014-200&&(m.month<9||(m.month==9&&m.day<6)))
	return 0;
	return 1;	
}
int compare(old_man a,old_man b)
{
	if(a.year!=b.year)
	return b.year-a.year;
	if(a.month!=b.month)
	return b.month-a.month;
	return b.day-a.day;
}
int main()
{
	int n,youxiao=0,i;
	old_man max,min,current,temp;
	max.day=31,max.year=2015,max.month=12;
	min.day=0,min.year=0,min.month=0;
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%s %d/%d/%d",current.name,&(current.year),&(current.month),&(current.day));
		if(valid(current))
		youxiao++;
		else
		continue;
		if(compare(max,current)<0)
		{
			max=current;
		}
		if(compare(current,min)<0)
		{
			min=current;
		}
	}
	if(youxiao)
	printf("%d %s %s\n",youxiao,max.name,min.name);
	else
	printf("%d\n",youxiao);
	return 0;
}