閉路検出 (lib/graph/cycle.hpp)

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Last update: 2025-06-10 13:56:45+09:00
Include: #include "lib/graph/cycle.hpp"

Depends on

重み付きグラフ (lib/graph/graph.hpp)

Verified with

test/aoj/grl/cycle.test.cpp

Code

#pragma once
#include <vector>
#include "graph/graph.hpp"

/// @brief 閉路検出
template <class T>
bool has_cycle(const Graph<T> &g) {
    int n = g.size();
    std::vector<bool> seen(n), finished(n);
    bool res = false;

    auto dfs = [&](auto self, int index) -> void {
        if (finished[index]) return;
        seen[index] = true;
        for (auto &e : g[index]) {
            if (res |= seen[e.to()]) return;
            self(self, e.to());
        }
        seen[index] = false;
        finished[index] = true;
    };

    for (int i = 0; i < n; ++i) {
        if (res) break;
        dfs(dfs, i);
    }
    return res;
}

Traceback (most recent call last):
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/resolver.py", line 291, in resolve
    bundled_code = language.bundle(path, basedir=basedir)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/verify/languages/cplusplus.py", line 242, in bundle
    bundler.update(path)
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/verify/languages/cplusplus_bundle.py", line 479, in update
    self._resolve(pathlib.Path(included), included_from=path)
  File "/home/runner/.local/lib/python3.12/site-packages/competitive_verifier/oj/verify/languages/cplusplus_bundle.py", line 286, in _resolve
    raise BundleErrorAt(path, -1, "no such header")
competitive_verifier.oj.verify.languages.cplusplus_bundle.BundleErrorAt: graph/graph.hpp: line -1: no such header