蒟蒻的代码（列举）

#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long week[3003],y1,y2,sum=0;
	week[1900]=7;//星期日（7）
	cin>>y1>>y2;
	for(int i=1901;i<=3000;i++)
	{
		if(i/100!=0)
		{
			if(i/4==0)
				week[i]=week[i-1]+2;
			else
				week[i]=week[i-1]+1;
		}
		if(i/100==0)
		{
			if(i/400==0)
				week[i]=week[i-1]+2;
			else
				week[i]=week[i-1]+1;
		}
		
		if(week[i]==8)
			week[i]=1;
		if(week[i]==9)
			week[i]=2;
	}
	for(int i=y1;i<=y2;i++)
	{
		if(week[i]==7||week[i]==6)
			sum++;
	}
	cout<<sum<<"\n";
	return 0;
}