graph/func/cycles.hpp

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• Last update: 2024-11-09 00:49:07+00:00
• Include: #include "graph/func/cycles.hpp"

Depends on

• prelude.hpp

Code

#pragma once
#include "prelude.hpp"

template <class It>
vector<vector<int>> cycles(It first, It last) {
  int n = last - first;
  vector<int> from(n, -1);
  vector<vector<int>> res;
  rep(s, n) if (from[s] == -1) {
    int v = s;
    for (; from[v] == -1; v = first[v]) from[v] = s;
    if (from[v] == s) {
      vector<int> c = {v};
      for (v = first[v]; v != c[0]; v = first[v]) c.push_back(v);
      res.push_back(move(c));
    }
  }
  return res;
}

#line 2 "prelude.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vll = vector<ll>;
using vvll = vector<vector<ll>>;
using vc = vector<char>;
#define rep2(i, m, n) for (auto i = (m); i < (n); i++)
#define rep(i, n) rep2(i, 0, n)
#define repr2(i, m, n) for (auto i = (n); i-- > (m);)
#define repr(i, n) repr2(i, 0, n)
#define all(x) begin(x), end(x)
auto ndvec(int n, auto e) { return vector(n, e); }
auto ndvec(int n, auto ...e) { return vector(n, ndvec(e...)); }
auto comp_key(auto&& f) { return [&](auto&& a, auto&& b) { return f(a) < f(b); }; }
auto& max(const auto& a, const auto& b) { return a < b ? b : a; }
auto& min(const auto& a, const auto& b) { return b < a ? b : a; }
#if __cpp_lib_ranges
namespace R = std::ranges;
namespace V = std::views;
#endif
#line 3 "graph/func/cycles.hpp"

template <class It>
vector<vector<int>> cycles(It first, It last) {
  int n = last - first;
  vector<int> from(n, -1);
  vector<vector<int>> res;
  rep(s, n) if (from[s] == -1) {
    int v = s;
    for (; from[v] == -1; v = first[v]) from[v] = s;
    if (from[v] == s) {
      vector<int> c = {v};
      for (v = first[v]; v != c[0]; v = first[v]) c.push_back(v);
      res.push_back(move(c));
    }
  }
  return res;
}

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