Shared code

#pragma GCC optimize("O3", "inline")
#include <bits/stdc++.h>
using namespace std;

typedef long long int ll;
typedef long double ld;
#define pb push_back
#define ub upper_bound

const ll INF = 1e18 + 100;

vector<int> solve()
{
    int n;
    cin >> n;
    if(n == 4) return {2, 4, 1, 3};
    if(n == 1) return {1};
    if(n <= 3) return {-1};
    vector<int> ansa(n);
    int gps = n / 5;
    int ptr = 0;
    for(int i = 1; i <= gps * 5; i += 5){
        ansa[ptr] = i;
        ansa[ptr + 1] = i + 2;
        ansa[ptr + 2] = i + 4;
        ansa[ptr + 3] = i + 1;
        ansa[ptr + 4] = i + 3;
        ptr += 5;
    }
    int rem = n % 5;
    if(!rem) return ansa;
    int nextNum = gps * 5 + 1;
    if(rem == 1) {
        ansa[ptr] = n;
        return ansa;
    }
    if(rem == 2) {
        ansa[ptr] = ansa[ptr - 1];
        ansa[ptr - 1] = nextNum;
        ansa[n - 1] = n;
        return ansa;
    }
    if(rem == 3){
        ansa[ptr + 1] = ansa[ptr - 1];
        ansa[ptr - 1] = nextNum;
        ansa[ptr] = nextNum + 2;
        ansa[n - 1] = n - 1;
        return ansa;
    }
    if(rem == 4){
        ansa[ptr] = nextNum + 1;
        ansa[ptr + 1] = nextNum + 3;
        ansa[ptr + 2] = nextNum;
        ansa[ptr + 3] = nextNum + 2;
        return ansa;
    }
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    while(t--)
    {
        vector<int> ansa = solve();
        if(ansa[0] == -1) cout << "NO SOLUTION\n";
        else{
            for(int x: ansa) cout << x << " ";
        }
    }
    return 0;
}