【CCF】有趣的数 数位dp

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<string>
 5 #include<cmath>
 6 #include<algorithm>
 7 #include<queue>
 8 #include<map>
 9 using namespace std;
10 const int mod=1e9+7;
11 const int maxn=1e3+2;
12 int dp[maxn][6];
13 void pre(){
14     memset(dp,0,sizeof(dp));
15     dp[1][0]=1;
16     for(int i=2;i<maxn;i++){
17         dp[i][0]=1;
18         dp[i][1]=((dp[i-1][1]*2)%mod+dp[i-1][0])%mod;
19         dp[i][2]=(dp[i-1][2]+dp[i-1][0])%mod;
20         dp[i][3]=(dp[i-1][1]+(dp[i-1][3]*2)%mod)%mod;
21         dp[i][4]=((dp[i-1][1]+dp[i-1][2])%mod+(dp[i-1][4]*2)%mod)%mod;
22         dp[i][5]=((dp[i-1][3]+dp[i-1][4])%mod+dp[i-1][5]*2%mod)%mod;
23     }
24 }
25 int n;
26 int main(){
27     pre();
28     while(~scanf("%d",&n)){
29         printf("%d\n",dp[n][5]);
30     }
31     return 0;
32 }