3-Coloring

#include <bits/stdc++.h>

using namespace std;

// 3-coloring problem

/*
You are given a directed graph with n nodes and n edges. Node i has exactly one outgoing edge that leads to node e_i. Your task is to find a valid 3-coloring of the graph: the endpoints of each edge should have different colors and you can only use at most 3 colors. It is guaranteed that the graph does not contain any self-loops and it can be proven that a valid coloring always exists when this constraint is met.
Input
The first line contains one integer n: the number of nodes.
The second line contains n integers e_1,\ e_2,\ \dots,\ e_n: the edges.
Output
Print n integers in the range [1, 3] on a single line. The output should be a valid coloring for the nodes.
*/

int main()
{
    // ios_base::sync_with_stdio(0);
    // cin.tie(0);

    int n;
    cin >> n;

    priority_queue<pair<int, int>> pq;
    for (int i = 0; i < n; ++i) {
        int node1 = i;
        int node2;
        cin >> node2;
        --node2;

        pq.push({max(node1, node2), min(node1, node2)});
    }

    vector<int> color(n, 1);
    while (!pq.empty()) {
        pair<int, int> edge = pq.top();
        int node1 = edge.first;
        int node2 = edge.second;
        if (color[node1] == color[node2]) {
            color[node2] = ((color[node1] % 3) + 1);
        }
        pq.pop();
    }

    for (int i = 0; i < n; ++i) {
        cout << color[i] << " ";
    }
    cout << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER