dwd

auto unionGroups = [&](int a, int b, int time) {
            int rootA = find(a);
            int rootB = find(b);
            if (rootA != rootB) {
                // Merge lower rank root into higher rank root
                if (rank[rootA] > rank[rootB]) {
                    parent[rootB] = rootA;
                    if (infectionTime[rootA] != -1 && infectionTime[rootB] == -1 && !vaccinated[rootB]) {
                        infectionTime[rootB] = time;
                    }
                } else if (rank[rootA] < rank[rootB]) {
                    parent[rootA] = rootB;
                    if (infectionTime[rootB] != -1 && infectionTime[rootA] == -1 && !vaccinated[rootA]) {
                        infectionTime[rootA] = time;
                    }
                } else {
                    parent[rootB] = rootA;
                    rank[rootA]++;
                    if (infectionTime[rootA] != -1 && infectionTime[rootB] == -1 && !vaccinated[rootB]) {
                        infectionTime[rootB] = time;
                    } else if (infectionTime[rootB] != -1 && infectionTime[rootA] == -1 && !vaccinated[rootA]) {
                        infectionTime[rootA] = time;
                    }
                }
            }
        };