///@author Sycamore ///@date 9/11/2017 ///@link http://acm.hdu.edu.cn/showproblem.php?pid=2569 #include<bits/stdc++.h> using namespace std; int num[40]; int main() { num[1] = 3; num[2] = 9; for (int i = 3; i < 40; i++) num[i] = 2 * num[i - 1] + num[i - 2]; ios::sync_with_stdio(false); cin.tie(0); int c; cin >> c; while (c--) { int n; cin >> n; cout << num[n] << ‘\n‘; } return 0; }
原文：http://www.cnblogs.com/zjnu/p/7507266.html