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#include "C++/graph/mst/kruskal.hpp"
#pragma once #include <vector> #include "C++/graph/mst/MST.hpp" #include "C++/ds/uf/UnionFind.hpp" inline MST kruskal(std::vector<edge> edges, const int n) { std::sort(edges.begin(), edges.end(), [&](const edge &e, const edge &f){ return e.cost < f.cost; }); UnionFind uf(n); std::vector<edge> e; long long res = 0; for(const auto &ed: edges) { if(uf.unite(ed.src, ed)) { e.emplace_back(ed); res += ed.cost; } } return {e, res}; } /** * @brief Kruskal法 */
#line 2 "C++/graph/mst/kruskal.hpp" #include <vector> #line 2 "C++/graph/mst/MST.hpp" #line 2 "C++/graph/edge.hpp" struct edge { int src, to, id; long long cost; edge(){} edge(const int src_, const int to_, const int id_ = -1, const long long cost_ = 0): src(src_), to(to_), id(id_), cost(cost_){} operator int() const { return to; } }; /** * @brief Edge */ #line 5 "C++/graph/mst/MST.hpp" struct MST { std::vector<edge> tree; long long cost; }; /** * @brief 最小全域木 */ #line 2 "C++/ds/uf/UnionFind.hpp" #include <cassert> #line 5 "C++/ds/uf/UnionFind.hpp" #include <algorithm> struct UnionFind { protected: std::vector<int> par; public: UnionFind(const int n): par(n, -1){} int operator[](int i) { while(par[i] >= 0) { const int p = par[par[i]]; if(p < 0) return par[i]; i = par[i] = p; } return i; } bool unite(int x, int y) { x = (*this)[x], y = (*this)[y]; if(x == y) return false; if(-par[x] < -par[y]) { std::swap(x, y); } par[x] += par[y], par[y] = x; return true; } int size(const int x) { return -par[(*this)[x]]; } int size() const { return par.size(); } #if __cplusplus >= 202101L std::vector<std::vector<int>> groups() { const int n = std::ssize(par); std::vector<std::vector<int>> res(n); for(int i = 0; i < n; ++i) { res[(*this)[i]].emplace_back(i); } const auto it = std::ranges::remove_if(res, [&](const std::vector<int> &v){ return v.empty(); }); res.erase(it.begin(), it.end()); return res; } #else std::vector<std::vector<int>> groups() { const int n = par.size(); std::vector<std::vector<int>> res(n); for(int i = 0; i < n; ++i) { res[(*this)[i]].emplace_back(i); } res.erase(std::remove_if(res.begin(), res.end(), [&](const std::vector<int> &v){ return v.empty(); }), res.end()); return res; } #endif }; inline bool is_bipartite(UnionFind uf) { assert(uf.size() % 2 == 0); const int n = uf.size() / 2; bool ok = true; for(int i = 0; i < n; ++i) { ok &= uf[i] != uf[i + n]; } return ok; } /** * @brief UnionFind * @see https://github.com/maspypy/library/blob/main/ds/unionfind/unionfind.hpp */ #line 6 "C++/graph/mst/kruskal.hpp" inline MST kruskal(std::vector<edge> edges, const int n) { std::sort(edges.begin(), edges.end(), [&](const edge &e, const edge &f){ return e.cost < f.cost; }); UnionFind uf(n); std::vector<edge> e; long long res = 0; for(const auto &ed: edges) { if(uf.unite(ed.src, ed)) { e.emplace_back(ed); res += ed.cost; } } return {e, res}; } /** * @brief Kruskal法 */