lightoj 1136 第一次打表找規律做題..

#include<stdio.h>
typedef long long ll;
ll getNum(ll n)
{
	if(n==1)
		return 0;
	ll sum=2*((n+1)/3)-1;
	if((n+1)%3==0)
		return sum;
	return sum+1;
		
}
int main()
{
	int cas;
	scanf("%d",&cas);
	for(int T=1;T<=cas;T++)
	{
		ll a,b;
		ll ans=0;
		scanf("%lld%lld",&a,&b);
		if(a==1)
			ans=getNum(b);
		else
			ans=getNum(b)-getNum(a-1);
		printf("Case %d: %lld\n",T,ans);
	}
	return 0;
}