dsu

struct dsu {
    int n, unions;
    vector<int> t, count;

    dsu(int nn) {
        n = nn;
        unions = n;

        t.assign(n, 0);
        for (int i = 0; i < n; i++) t[i] = i;
        count.assign(n, 1);
    }

    int find(int i) {
        if (i == t[i]) return i;
        return t[i] = find(t[i]);
    }

    bool unite(int a, int b) {
        a = find(a);
        b = find(b);

        if (a == b) return 0;
        unions--;

        if (count[a] > count[b]) swap(a, b);

        t[a] = b;
        count[b] += count[a];
        return 1;
    }
};