九度教程第7题

题目地址：http://ac.jobdu.com/problem.php?cid=1040&pid=6

C语言源码：

#include<stdio.h>
#include<string.h>
int leap(int year)
{
	if((year%4==0&&year%100!=0)||year%400==0)
		return 1;
	else
		return 0;
}//判断是不是闰年
int daynum(int year,int month,int day)
{
	int i,sum;
	i=1;
	sum=0;
	while(i<month)
	{
		if(i==1||i==3||i==5||i==7||i==8||i==10||i==12)
			sum+=31;
		else
			if(i!=2)
				sum+=30;
			else
				if(leap(year))
					sum+=29;
				else
					sum+=28;
			i++;
	}
	return sum+day;
}//计算距离当年1月1号的天数
int main()
{
	char mon[12][10]={"January","February","March","April","May","June","July","August","September","October","November","December"};
	char we[7][10]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};
	int i,day,year,month,week,sum;
	char m[10];
	while(scanf("%d %s %d",&day,m,&year)!=EOF)
	{
		for(i=0;i<12;i++)
		{
			if(strcmp(m,mon[i])==0)
				month=i+1;
		}
		sum=0;
		if(year==2013)
			sum=daynum(year,month,day)-daynum(2013,1,17);
		else
			if(year>2013)
			{
				i=2014;
				while(i<year)
				{
					if(leap(i))
						sum+=366;
					else
						sum+=365;
					i++;
				}
				sum+=365-daynum(2013,1,17)+daynum(year,month,day);
			}
			else
			{
				i=year+1;
				while(i<2013)
				{
					if(leap(i))
						sum+=366;
					else
						sum+=365;
					i++;
				}
				sum+=365+daynum(2013,1,17)-daynum(year,month,day);
				if(leap(year))
					sum+=1;
				sum=-sum;
			}//计算输入年份与2013年1月17号的差距天数，有正负
			week=((4+sum)%7+7)%7;
			printf("%s\n",we[week]);
	}
}