test/library-checker/persistent_unionfind.test.cpp

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• Last update: 2026-10-26 01:30:50+09:00
• Problem: https://judge.yosupo.jp/problem/persistent_unionfind

Depends on

• Rollback DSU (datastructure/rollback_dsu.hpp)

Code

#define PROBLEM "https://judge.yosupo.jp/problem/persistent_unionfind"
#include <iostream>
#include <vector>

#include "datastructure/rollback_dsu.hpp"

int main() {
    int n, q;
    std::cin >> n >> q;
    std::vector<int> t(q), k(q), u(q), v(q);
    // version tree: node q is G_{-1}; type-0 query i is node i with parent k
    std::vector<std::vector<int>> children(q + 1), asks(q + 1);
    for (int i = 0; i < q; i++) {
        std::cin >> t[i] >> k[i] >> u[i] >> v[i];
        int p = k[i] == -1 ? q : k[i];
        if (t[i] == 0) {
            children[p].push_back(i);
        } else {
            asks[p].push_back(i);
        }
    }
    std::vector<int> ans(q, -1);
    rollback_dsu d(n);
    std::vector<std::pair<int, int>> st = {{q, 0}};  // (node, next child index)
    while (!st.empty()) {
        auto& [x, it] = st.back();
        if (it == 0) {
            if (x != q) d.merge(u[x], v[x]);
            for (int i : asks[x]) ans[i] = d.same(u[i], v[i]);
        }
        if (it < int(children[x].size())) {
            int c = children[x][it++];
            st.emplace_back(c, 0);
        } else {
            if (x != q) d.undo();
            st.pop_back();
        }
    }
    for (int i = 0; i < q; i++) {
        if (t[i] == 1) std::cout << ans[i] << '\n';
    }
}

#line 1 "test/library-checker/persistent_unionfind.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/persistent_unionfind"
#include <iostream>
#include <vector>

#line 2 "datastructure/rollback_dsu.hpp"
#include <algorithm>
#include <cassert>
#include <utility>
#line 6 "datastructure/rollback_dsu.hpp"
struct rollback_dsu {
public:
    rollback_dsu() : rollback_dsu(0) {
    }
    explicit rollback_dsu(int n) : _n(n), parent_or_size(n, -1) {
    }
    int merge(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        int x = leader(a), y = leader(b);
        if (x == y) {
            history.emplace_back(-1, -1);
            return x;
        }
        if (-parent_or_size[x] < -parent_or_size[y]) std::swap(x, y);
        history.emplace_back(y, parent_or_size[y]);
        parent_or_size[x] += parent_or_size[y];
        parent_or_size[y] = x;
        return x;
    }
    void undo() {
        assert(!history.empty());
        auto [y, s] = history.back();
        history.pop_back();
        if (y == -1) return;
        parent_or_size[parent_or_size[y]] -= s;
        parent_or_size[y] = s;
    }
    int time() const {
        return int(history.size());
    }
    void rollback(int t) {
        assert(0 <= t && t <= time());
        while (time() > t) undo();
    }
    bool same(int a, int b) const {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        return leader(a) == leader(b);
    }
    int leader(int a) const {
        assert(0 <= a && a < _n);
        while (parent_or_size[a] >= 0) a = parent_or_size[a];
        return a;
    }
    int size(int a) const {
        assert(0 <= a && a < _n);
        return -parent_or_size[leader(a)];
    }
    std::vector<std::vector<int>> groups() const {
        std::vector<int> leader_buf(_n), group_size(_n);
        for (int i = 0; i < _n; i++) {
            leader_buf[i] = leader(i);
            group_size[leader_buf[i]]++;
        }
        std::vector<std::vector<int>> result(_n);
        for (int i = 0; i < _n; i++) result[i].reserve(group_size[i]);
        for (int i = 0; i < _n; i++) result[leader_buf[i]].push_back(i);
        result.erase(std::remove_if(result.begin(), result.end(),
                                    [&](const std::vector<int>& v) { return v.empty(); }),
                     result.end());
        return result;
    }

private:
    int _n;
    std::vector<int> parent_or_size;
    std::vector<std::pair<int, int>> history;  // (attached leader, its old parent_or_size)
};
#line 6 "test/library-checker/persistent_unionfind.test.cpp"

int main() {
    int n, q;
    std::cin >> n >> q;
    std::vector<int> t(q), k(q), u(q), v(q);
    // version tree: node q is G_{-1}; type-0 query i is node i with parent k
    std::vector<std::vector<int>> children(q + 1), asks(q + 1);
    for (int i = 0; i < q; i++) {
        std::cin >> t[i] >> k[i] >> u[i] >> v[i];
        int p = k[i] == -1 ? q : k[i];
        if (t[i] == 0) {
            children[p].push_back(i);
        } else {
            asks[p].push_back(i);
        }
    }
    std::vector<int> ans(q, -1);
    rollback_dsu d(n);
    std::vector<std::pair<int, int>> st = {{q, 0}};  // (node, next child index)
    while (!st.empty()) {
        auto& [x, it] = st.back();
        if (it == 0) {
            if (x != q) d.merge(u[x], v[x]);
            for (int i : asks[x]) ans[i] = d.same(u[i], v[i]);
        }
        if (it < int(children[x].size())) {
            int c = children[x][it++];
            st.emplace_back(c, 0);
        } else {
            if (x != q) d.undo();
            st.pop_back();
        }
    }
    for (int i = 0; i < q; i++) {
        if (t[i] == 1) std::cout << ans[i] << '\n';
    }
}

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