poj2663

poj2411的弱化版http://www.cnblogs.com/yzcstc/archive/2013/03/23/2977689.html

/*
  State:Accepted
  Time:2013-03-19 20:41:08
*/
#include <iostream>
#include <cstring>
#include <string>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <cmath>
using namespace std;
const int m = 3;
const int maxn = 30;
int f[32][30] ,data , n;

void updata(int i , int opt , int pos){
     if (pos == m){
         f[i][opt] += data;   
         return; 
     }
     updata(i, opt , pos + 1);
     if ((opt & (1 << pos-1)) == 0 && (opt & (1 << pos)) == 0)
           updata(i, opt | (1 << pos -1) | (1 << pos), pos + 1);
     
}

void dp(){
     data = 1;
     updata(1 , 0 , 1);
     for (int i = 1; i < maxn; ++i)
         for (int opt = 0; opt < (1 << m); ++opt)
            if (f[i][opt] ){
                 data = f[i][opt];
                 updata(i + 1,  ~ opt &  7, 1 ); 
            }
   /*  for (int i = 1; i <= 2; ++i)
        for (int  opt =0; opt < 8; ++opt)
           printf("f[%d][%d] = %d\n",i ,opt , f[i][opt]);*/
}

int main(){
     freopen("poj2663.in","r",stdin);
     freopen("poj2663.out","w",stdout);
     dp();
     while (~scanf("%d",&n) && n != -1){
          if (n == 0) printf("1\n");
          else printf("%d\n",f[n][7]);
     }
     fclose(stdin); fclose(stdout);
}