test/library-checker/connected_components_of_complement_graph.test.cpp

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• Last update: 2024-06-29 13:06:37+09:00
• Problem: https://judge.yosupo.jp/problem/connected_components_of_complement_graph

Depends on

• graph/bfs_tree_of_complement.hpp

Code

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

#include "graph/bfs_tree_of_complement.hpp"
int main() {
    int n, m;
    std::cin >> n >> m;
    std::vector<std::vector<int>> g(n);
    for (int i = 0; i < m; i++) {
        int u, v;
        std::cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    std::vector adj = bfs_tree_of_complement(g);
    std::vector<std::vector<int>> ans;
    std::vector used(n, false);
    auto dfs = [&](auto dfs, int u) -> void {
        used[u] = true;
        ans.back().push_back(u);
        for (int v : adj[u]) {
            dfs(dfs, v);
        }
    };
    for (int i = 0; i < n; i++) {
        if (used[i]) continue;
        ans.push_back({});
        dfs(dfs, i);
    }
    int k = ans.size();
    std::cout << k << '\n';
    for (const std::vector<int>& v : ans) {
        int l = v.size();
        std::cout << l << ' ';
        for (int i = 0; i < l; i++) {
            std::cout << v[i] << " \n"[i == l - 1];
        }
    }
}

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

#line 2 "graph/bfs_tree_of_complement.hpp"
#include <algorithm>
#include <numeric>
#include <queue>
#include <vector>
std::vector<std::vector<int>> bfs_tree_of_complement(
    const std::vector<std::vector<int>>& g) {
    int n = int(g.size());
    std::vector<std::vector<int>> ret(n);
    std::vector<bool> seen(n);
    std::vector<bool> banned(n);
    std::queue<int> q;
    std::vector<int> s(n), t;
    std::iota(s.begin(), s.end(), 0);
    for (int i = 0; i < n; i++) {
        if (seen[i]) continue;
        seen[i] = true;
        q.push(i);
        while (!q.empty()) {
            int u = q.front();
            q.pop();
            seen[u] = true;
            for (int v : g[u]) {
                banned[v] = true;
            }
            for (int v : s) {
                if (banned[v]) {
                    t.push_back(v);
                } else if (!seen[v]) {
                    ret[u].push_back(v);
                    q.push(v);
                }
            }
            s = std::move(t);
            for (int v : g[u]) {
                banned[v] = false;
            }
        }
    }
    return ret;
}
#line 6 "test/library-checker/connected_components_of_complement_graph.test.cpp"
int main() {
    int n, m;
    std::cin >> n >> m;
    std::vector<std::vector<int>> g(n);
    for (int i = 0; i < m; i++) {
        int u, v;
        std::cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    std::vector adj = bfs_tree_of_complement(g);
    std::vector<std::vector<int>> ans;
    std::vector used(n, false);
    auto dfs = [&](auto dfs, int u) -> void {
        used[u] = true;
        ans.back().push_back(u);
        for (int v : adj[u]) {
            dfs(dfs, v);
        }
    };
    for (int i = 0; i < n; i++) {
        if (used[i]) continue;
        ans.push_back({});
        dfs(dfs, i);
    }
    int k = ans.size();
    std::cout << k << '\n';
    for (const std::vector<int>& v : ans) {
        int l = v.size();
        std::cout << l << ' ';
        for (int i = 0; i < l; i++) {
            std::cout << v[i] << " \n"[i == l - 1];
        }
    }
}

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