其实没必要用数组

#include <iostream>
using namespace std;

int main(){
int n;
cin >> n;
int x = 2;
for(int i = 1;i <= n;i++){
cout << x << " ";
if(i % 2 == 1){
x -= 1;
}else{
x += 3;
}
}
return 0;
}