Graph painting

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>

using namespace std;

int coloring[100000];

int main(int argc, char *argv[])
{
    int t;
    cin >> t;

    for (int i = 0; i < t; ++i) {
        int n, m;
        cin >> n >> m;

        for (int j = 0; j < m; ++j) {
            int a, b;
            cin >> a >> b;
            a--;
            b--;

            if (coloring[a] == 0 && coloring[b] == 0) {
                coloring[a] = 1;
                coloring[b] = 2;
            } else if (coloring[a] == 1 && coloring[b] == 0) {
                coloring[b] = 2;
            } else if (coloring[a] == 2 && coloring[b] == 0) {
                coloring[b] = 1;
            } else if (coloring[a] == 0 && coloring[b] == 1) {
                coloring[a] = 2;
            } else if (coloring[a] == 0 && coloring[b] == 2) {
                coloring[a] = 1;
            }
        }

        for (int i = 0; i < n; ++i) {
            printf(coloring[i] == 1 ? "R " : "B ");
        }

        printf("\n");

        memset(coloring, 0, 100000);
    }

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED