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  1. #include <iostream>
  2. #include <vector>
  3. #define int unsigned long long
  4. //const int MOD = 1e9+7;
  5. using namespace std;
  6. main() {
  7.     int n;
  8.     while(cin >> n){
  9.     	if (n >= 3) {
  10.     		vector<int> dp(n + 1, 0);
  11.     		dp[0] = 1;
  12.     		dp[1] = 2;
  13.     		dp[2] = 7;
  14.     		vector<int> prex(n - 1, 0);
  15.     		prex[0] = 1;
  16.     		for (int i = 3; i <= n; i++) {
  17.     			prex[i - 2] = prex[i - 3] + dp[i - 2];
  18.     			dp[i] = 2 * dp[i - 1] + 3 * dp[i - 2] + 2 * prex[i - 3];}
  19.     		cout << dp[n];
  20.     	}
  21.     }
  22.     return 0;
  23. }
Success #stdin #stdout 0.01s 5436KB
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https://ideone.com/mETwSa
language:
C++ (gcc 8.3)
created:
2 years ago
visibility:
public

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