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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define lli long long int
  4. const lli MOD=1e09+7; 
  5. #define rep(i,n) for(int i=0;i<n;i++)
  6. int main(){
  7.     int t,n;
  8.     cin>>t;
  9.     while(t--){
  10.     	cin>>n;
  11.     	int k=9;
  12.     	lli dp[k+1][n+1];
  13.     	rep(i,k+1)rep(j,n+1)dp[i][j]=0;
  14.     	rep(i,n+1)dp[0][i]=1;
  15.     	for(int i=1;i<=k;i++){
  16.     		dp[i][1]=1;// having length 1 ,total lucky numbers is 1 for each i = 1,2,3,4,5,6,7,8,9
  17.     	}
  18.     	for(int j=2;j<=n;j++){//having length varying from 2 to n
  19.     		for(int i=1;i<=k;i++){// for i=1,2,3,4,5,6,7,8,9
  20.     			if(i==k)dp[i][j]=dp[i-1][j-1]%MOD;//9 has only 8 no next,9->8 
  21.     			else dp[i][j]=(dp[i-1][j-1]+dp[i+1][j-1])%MOD;//others has 2 8->7 and 8->9
  22.     		}
  23.     	}
  24.     	lli ans=0;
  25.     	for(int i=1;i<=k;i++){
  26.     		ans+=dp[i][n];
  27.     		ans%=MOD;
  28.     	}
  29.     	if(n==1)ans=(ans+1)%MOD;//if n==1 we include 0 
  30.     	cout<<ans%MOD<<"\n";
  31.     }
  32.     return 0;
  33. }
Runtime error #stdin #stdout 0s 3456KB
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Standard input is empty
stdout
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Standard output is empty
https://ideone.com/MFs8ou
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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