TOJ 1779.Tri Tiling

题目链接

思维逻辑题，百度了一下大神的递推过程，这里附上链接:http://blog.csdn.net/qiqijianglu/article/details/8082042

#include<iostream>  #include<cstdlib>  #include<stdio.h>  #define ll long long  using namespace std;  ll a[31];  int main()  {      ll n;      a[0]=1;a[2]=3;      for(int i=4;i<=30;i+=2)      a[i]=4*a[i-2]-a[i-4];      while(scanf("%lld",&n))      {          if(n==-1) break;          printf("%lld\n",a[n]);      }  }