coci14c4p5.cpp

// Ivan Carvalho
// Solution to https://dmoj.ca/problem/coci14c4p5
#include <bits/stdc++.h>
using namespace std;

const int MAXN = 2 * 1e5 + 10;

vector<int> grafo[MAXN];
int cor[MAXN], N;

int calcula_erro(int v) {
    int total = 0;
    for (int u : grafo[v]) total += (cor[v] == cor[u]);
    return total;
}

void dfs(int v) {
    int erros = calcula_erro(v);
    if (erros <= 2) {
        return;
    }
    cor[v] ^= 1;
    for (int u : grafo[v]) {
        dfs(u);
    }
}

int main() {
    scanf("%d", &N);
    for (int dia = 1; dia <= 5; dia++) {
        int pares;
        scanf("%d", &pares);
        while (pares--) {
            int u, v;
            scanf("%d %d", &u, &v);
            grafo[u].push_back(v);
            grafo[v].push_back(u);
        }
    }

    for (int i = 1; i <= N; i++) {
        sort(grafo[i].begin(), grafo[i].end());
        grafo[i].erase(unique(grafo[i].begin(), grafo[i].end()),
                       grafo[i].end());
    }

    for (int i = 1; i <= N; i++) {
        dfs(i);
    }

    for (int i = 1; i <= N; i++) {
        if (cor[i] == 0)
            printf("A");
        else
            printf("B");
    }
    printf("\n");

    return 0;
}