Split in Three

#include "bits/stdc++.h"
using namespace std;
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using ordered_set = tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>;
*/
 
#define all(x) begin(x), end(x)
#define sz(x) (int)x.size()
 
typedef long long ll;
const int mod = 1e9+7;
int n, sum;
vector<int> ans(3, 1e9);
 
void rec(vector<int> v, int x, int col) {
    v[col] |= (1 << x);
    int used = v[0] | v[1] | v[2];
    if (used == ((1<<(n+2)) - 2)) {
        vector<int> s(3);
        for (int i = 1; i <= n; ++i) {
            if (v[0]&(1<<i)) s[0] += i;
            if (v[1]&(1<<i)) s[1] += i;
            if (v[2]&(1<<i)) s[2] += i;
        }
        if (s[0] == s[1]-1 and s[2] == s[1]+1) {
            ans = v;
        }
        return;
    }
    for (int i = 0; i < 3; ++i) {
        rec(v, x+1, i);
    }
}
 
 
void solve(int tc) {
    cin >> n;
    sum = (n * (n + 1)) / 2;
    vector<int> col(n+1);
    rec(vector<int>(3), 1, 0);
    rec(vector<int>(3), 1, 1);
    rec(vector<int>(3), 1, 2);
    if (ans[0] != 1e9) {
        for (int i = 1; i <= n; ++i) {
            if (ans[0]&(1<<i)) cout << "1 ";
            if (ans[1]&(1<<i)) cout << "2 ";
            if (ans[2]&(1<<i)) cout << "3 ";
        }
        cout << '\n';
    } else {
        cout << "IMPOSSIBLE\n";
    }
}
 
signed main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int tc = 1;
    //cin >> tc;
    for (int i = 1; i <= tc; ++i) solve(i);
    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: WRONG ANSWER

Test 10

Group: 2

Verdict: RUNTIME ERROR

Test 11

Group: 2

Verdict: WRONG ANSWER

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: WRONG ANSWER

Test 14

Group: 2

Verdict: WRONG ANSWER

Test 15

Group: 2

Verdict: ACCEPTED