Kolmijako

/**
 * Datatähti 2021 loppu
 * 358
 * B
 * Kolmijako
 * @author TRS
 */
//Include
#include <bits/stdc++.h>
//Definitions
using namespace std;
//Constants
#define infinity 0x3f3f3f3f
#define linfinity 0x3f3f3f3f3f3f3f3f
#define MOD 1000000007
int n;
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin>>n;
    if ((n * (n + 1) / 2) % 3 != 0) {
        cout<<"IMPOSSIBLE"<<"\n";
        return 0;
    }
    if (n == 3) {
        cout<<"1 2 3"<<"\n";
        return 0;
    }
    if (n == 5) {
        cout<<"1 3 1 3 2"<<"\n";
        return 0;
    }
    if (n == 6) {
        cout<<"2 1 3 1 3 2"<<"\n";
        return 0;
    }
    if (n == 8) {
        cout<<"3 3 1 3 2 3 2 1"<<"\n";
        return 0;
    }
    if (n == 9) {
        cout<<"1 2 3 3 2 1 1 2 3"<<"\n";
        return 0;
    }
    if (n % 3 == 0) {
        if (n / 3 % 2 == 1) {
            for (int i = 0; i < n / 3 - 2; i++) {
                cout<<"1 2 3 3 2 1 ";
            }
            cout<<"1 2 3"<<"\n";
        }
        else {
            for (int i = 0; i < (n - 6) / 6; i++) {
                cout<<"1 2 3 ";
            }
            cout<<"2 1 3 1 3 2 ";
            for (int i = 0; i < (n - 6) / 6; i++) {
                cout<<"3 2 1 ";
            }
        }
    }
    else {
        for (int i = 0; i < (n - 5) / 6; i++) {
            cout<<"1 2 3 ";
        }
        cout<<"3 3 1 3 2 3 2 1 ";
        for (int i = 0; i < (n - 5) / 6; i++) {
            cout<<"3 2 1 ";
        }
    }
    return 0;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: WRONG ANSWER

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: WRONG ANSWER

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 2

Verdict: ACCEPTED