题解 | #小红的排列构造#

发现n>=3一定有解，前三个构造 3 2 1 即可。

#include<bits/stdc++.h>
#define int long long
#define double long double
#define x first
#define y second
using namespace std;
typedef long long LL;
typedef long long ll;
typedef pair<int,int> PII;
const int N=3e5+10;
const int M=1e3+10;
int mod=1e9+7;
int a[N];

void solve(){
    int n;cin>>n;
    if(n==1||n==2) cout<<"-1\n";
    else{
        cout<<"3 2 1 ";
        // cout<<n<<" ";
        for(int i=4;i<=n;i++) cout<<i<<" ";
        // cout<<1<<"\n";
    }
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    int _;
    _=1;
    //cin>>_;
    while(_--){
        solve();
    }
}