正解

正解：
#include <bits/stdc++.h>
using namespace std;
int n,a[24];
int main()
{
cin >> n;
a[1] = 1;
for (int i = 2;i <= n;i++)
{
if (i%2 == 0) a[i] = a[i - 1] * 2;
else a[i] = a[i - 1] + a[i - 2];
}
cout << a[n];
return 0;
}