sicily 1049. Mondriaan

画图找递推关系：

#include<iostream>
using namespace std;
int answer[1000010];
int main(){
	int N=0,L=0,ans=0,i=0;
	answer[0]=1;
	answer[1]=2;
	answer[2]=7;
	answer[3]= 2;
	answer[4]=1;
	for(i=5;i<1000010;++i){
		answer[i]=(3*answer[i-1]+answer[i-2]-answer[i-3]+10)%10;
	}
	cin>>N;
	for (i=0;i<N;++i){
		cin>>L;
		ans=answer[L];
		cout<<ans<<endl;
	}
	return 0;
}