rcpl

This documentation is automatically generated by online-judge-tools/verification-helper

View the Project on GitHub ruthen71/rcpl

:heavy_check_mark: verify/graph/lowest_common_ancestor_1.test.cpp

Depends on

Code

#define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_C"

#include <iostream>

#include "graph/read_graph.hpp"
#include "graph/lowest_common_ancestor.hpp"

int main() {
    int n;
    std::cin >> n;
    Graph<int> g(n, false);
    for (int i = 0; i < n; i++) {
        int k;
        std::cin >> k;
        for (int j = 0; j < k; j++) {
            int c;
            std::cin >> c;
            g.add_edge(i, c, 1);
        }
    }
    LowestCommonAncestor tq(g, 0);
    int q;
    std::cin >> q;
    while (q--) {
        int u, v;
        std::cin >> u >> v;
        std::cout << tq.lca(u, v) << '\n';
    }
    return 0;
}
#line 1 "verify/graph/lowest_common_ancestor_1.test.cpp"
#define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_C"

#include <iostream>

#line 2 "graph/read_graph.hpp"

#line 2 "graph/graph_template.hpp"

#include <vector>
#include <cassert>

template <class T> struct Edge {
    int from, to;
    T cost;
    int id;

    Edge() = default;
    Edge(const int from, const int to, const T cost = T(1), const int id = -1) : from(from), to(to), cost(cost), id(id) {}

    friend bool operator<(const Edge<T>& a, const Edge<T>& b) { return a.cost < b.cost; }

    friend std::ostream& operator<<(std::ostream& os, const Edge<T>& e) {
        // output format: {id: cost(from, to) = cost}
        return os << "{" << e.id << ": cost(" << e.from << ", " << e.to << ") = " << e.cost << "}";
    }
};
template <class T> using Edges = std::vector<Edge<T>>;

template <class T> struct Graph {
    struct EdgeIterators {
       public:
        using Iterator = typename std::vector<Edge<T>>::iterator;
        EdgeIterators() = default;
        EdgeIterators(const Iterator& begit, const Iterator& endit) : begit(begit), endit(endit) {}
        Iterator begin() const { return begit; }
        Iterator end() const { return endit; }
        size_t size() const { return std::distance(begit, endit); }
        Edge<T>& operator[](int i) const { return begit[i]; }

       private:
        Iterator begit, endit;
    };

    int n, m;
    bool is_build, is_directed;
    std::vector<Edge<T>> edges;

    // CSR (Compressed Row Storage) 形式用
    std::vector<int> start;
    std::vector<Edge<T>> csr_edges;

    Graph() = default;
    Graph(const int n, const bool directed = false) : n(n), m(0), is_build(false), is_directed(directed), start(n + 1, 0) {}

    // 辺を追加し, その辺が何番目に追加されたかを返す
    int add_edge(const int from, const int to, const T cost = T(1), int id = -1) {
        assert(!is_build);
        assert(0 <= from and from < n);
        assert(0 <= to and to < n);
        if (id == -1) id = m;
        edges.emplace_back(from, to, cost, id);
        return m++;
    }

    // CSR 形式でグラフを構築
    void build() {
        assert(!is_build);
        for (auto&& e : edges) {
            start[e.from + 1]++;
            if (!is_directed) start[e.to + 1]++;
        }
        for (int v = 0; v < n; v++) start[v + 1] += start[v];
        auto counter = start;
        csr_edges.resize(start.back() + 1);
        for (auto&& e : edges) {
            csr_edges[counter[e.from]++] = e;
            if (!is_directed) csr_edges[counter[e.to]++] = Edge(e.to, e.from, e.cost, e.id);
        }
        is_build = true;
    }

    EdgeIterators operator[](int i) {
        if (!is_build) build();
        return EdgeIterators(csr_edges.begin() + start[i], csr_edges.begin() + start[i + 1]);
    }

    size_t size() const { return (size_t)(n); }

    friend std::ostream& operator<<(std::ostream& os, Graph<T>& g) {
        os << "[";
        for (int i = 0; i < (int)(g.size()); i++) {
            os << "[";
            for (int j = 0; j < (int)(g[i].size()); j++) {
                os << g[i][j];
                if (j + 1 != (int)(g[i].size())) os << ", ";
            }
            os << "]";
            if (i + 1 != (int)(g.size())) os << ", ";
        }
        return os << "]";
    }
};
#line 4 "graph/read_graph.hpp"

template <class T> Graph<T> read_graph(const int n, const int m, const bool weight = false, const bool directed = false, const int offset = 1) {
    Graph<T> g(n, directed);
    for (int i = 0; i < m; i++) {
        int a, b;
        std::cin >> a >> b;
        a -= offset, b -= offset;
        T c = 1;
        if (weight) std::cin >> c;
        g.add_edge(a, b, c);
    }
    g.build();
    return g;
}

template <class T> Graph<T> read_parent(const int n, const bool weight = false, const bool directed = false, const int offset = 1) {
    Graph<T> g(n, directed);
    for (int i = 1; i < n; i++) {
        int p;
        std::cin >> p;
        p -= offset;
        T c = 1;
        if (weight) std::cin >> c;
        g.add_edge(p, i, c);
    }
    g.build();
    return g;
}
#line 2 "graph/lowest_common_ancestor.hpp"

#line 4 "graph/lowest_common_ancestor.hpp"

#line 6 "graph/lowest_common_ancestor.hpp"

template <class T> struct LowestCommonAncestor {
    int n, lg;
    std::vector<int> depth;
    std::vector<std::vector<int>> parent;

    LowestCommonAncestor(Graph<T>& g, const int root = 0) : n((int)(g.size())), lg(32 - __builtin_clz(n)), depth(n, 0), parent(lg, std::vector<int>(n)) {
        auto dfs = [&](auto f, int cur, int par) -> void {
            parent[0][cur] = par;
            for (auto&& e : g[cur]) {
                if (e.to == par) continue;
                depth[e.to] = depth[cur] + 1;
                f(f, e.to, cur);
            }
        };
        dfs(dfs, root, -1);
        for (int k = 0; k + 1 < lg; k++) {
            for (int v = 0; v < n; v++) {
                parent[k + 1][v] = parent[k][v] < 0 ? -1 : parent[k][parent[k][v]];
            }
        }
    }

    int lca(int u, int v) {
        assert((int)(depth.size()) == n);
        if (depth[u] > depth[v]) std::swap(u, v);
        // depth[u] <= depth[v]
        for (int k = 0; k < lg; k++) {
            if ((depth[v] - depth[u]) >> k & 1) v = parent[k][v];
        }
        if (u == v) return u;
        for (int k = lg - 1; k >= 0; k--) {
            if (parent[k][u] != parent[k][v]) {
                u = parent[k][u];
                v = parent[k][v];
            }
        }
        return parent[0][u];
    }

    int level_ancestor(int u, const int d) {
        assert((int)(depth.size()) == n);
        if (depth[u] < d) return -1;
        for (int k = 0; k < lg; k++) {
            if (d >> k & 1) u = parent[k][u];
        }
        return u;
    }

    int distance(const int u, const int v) const { return depth[u] + depth[v] - 2 * depth[lca(u, v)]; }
};
#line 7 "verify/graph/lowest_common_ancestor_1.test.cpp"

int main() {
    int n;
    std::cin >> n;
    Graph<int> g(n, false);
    for (int i = 0; i < n; i++) {
        int k;
        std::cin >> k;
        for (int j = 0; j < k; j++) {
            int c;
            std::cin >> c;
            g.add_edge(i, c, 1);
        }
    }
    LowestCommonAncestor tq(g, 0);
    int q;
    std::cin >> q;
    while (q--) {
        int u, v;
        std::cin >> u >> v;
        std::cout << tq.lca(u, v) << '\n';
    }
    return 0;
}
Back to top page