C++ Library for Competitive Programming
/*
* @title グラフ/Kruskal 法
*
* verification-helper: PROBLEM http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_2_A
*/
#include <iostream>
#include <vector>
#include "emthrm/graph/edge.hpp"
#include "emthrm/graph/kruskal.hpp"
int main() {
int v, e;
std::cin >> v >> e;
std::vector<std::vector<emthrm::Edge<long long>>> edge(v);
for (int i = 0; i < e; ++i) {
int s, t, w;
std::cin >> s >> t >> w;
edge[s].emplace_back(s, t, w);
edge[t].emplace_back(t, s, w);
}
std::cout << emthrm::kruskal(edge) << '\n';
return 0;
}
#line 1 "test/graph/kruskal.test.cpp"
/*
* @title グラフ/Kruskal 法
*
* verification-helper: PROBLEM http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_2_A
*/
#include <iostream>
#include <vector>
#line 1 "include/emthrm/graph/edge.hpp"
/**
* @title 辺
*/
#ifndef EMTHRM_GRAPH_EDGE_HPP_
#define EMTHRM_GRAPH_EDGE_HPP_
#include <compare>
namespace emthrm {
template <typename CostType>
struct Edge {
CostType cost;
int src, dst;
explicit Edge(const int src, const int dst, const CostType cost = 0)
: cost(cost), src(src), dst(dst) {}
auto operator<=>(const Edge& x) const = default;
};
} // namespace emthrm
#endif // EMTHRM_GRAPH_EDGE_HPP_
#line 1 "include/emthrm/graph/kruskal.hpp"
#include <algorithm>
#include <ranges>
#line 7 "include/emthrm/graph/kruskal.hpp"
#line 1 "include/emthrm/data_structure/union-find/union-find.hpp"
#include <utility>
#line 6 "include/emthrm/data_structure/union-find/union-find.hpp"
namespace emthrm {
struct UnionFind {
explicit UnionFind(const int n) : data(n, -1) {}
int root(const int ver) {
return data[ver] < 0 ? ver : data[ver] = root(data[ver]);
}
bool unite(int u, int v) {
u = root(u);
v = root(v);
if (u == v) return false;
if (data[u] > data[v]) std::swap(u, v);
data[u] += data[v];
data[v] = u;
return true;
}
bool is_same(const int u, const int v) { return root(u) == root(v); }
int size(const int ver) { return -data[root(ver)]; }
private:
std::vector<int> data;
};
} // namespace emthrm
#line 1 "include/emthrm/graph/edge.hpp"
/**
* @title 辺
*/
#ifndef EMTHRM_GRAPH_EDGE_HPP_
#define EMTHRM_GRAPH_EDGE_HPP_
#include <compare>
namespace emthrm {
template <typename CostType>
struct Edge {
CostType cost;
int src, dst;
explicit Edge(const int src, const int dst, const CostType cost = 0)
: cost(cost), src(src), dst(dst) {}
auto operator<=>(const Edge& x) const = default;
};
} // namespace emthrm
#endif // EMTHRM_GRAPH_EDGE_HPP_
#line 10 "include/emthrm/graph/kruskal.hpp"
namespace emthrm {
template <typename CostType>
CostType kruskal(const std::vector<std::vector<Edge<CostType>>>& graph) {
const int n = graph.size();
const auto jv = graph | std::views::join;
std::vector<Edge<CostType>> edges(jv.begin(), jv.end());
std::ranges::sort(edges);
CostType res = 0;
UnionFind uf(n);
for (const Edge<CostType>& e : edges) {
if (uf.unite(e.src, e.dst)) res += e.cost;
}
return res;
}
} // namespace emthrm
#line 12 "test/graph/kruskal.test.cpp"
int main() {
int v, e;
std::cin >> v >> e;
std::vector<std::vector<emthrm::Edge<long long>>> edge(v);
for (int i = 0; i < e; ++i) {
int s, t, w;
std::cin >> s >> t >> w;
edge[s].emplace_back(s, t, w);
edge[t].emplace_back(t, s, w);
}
std::cout << emthrm::kruskal(edge) << '\n';
return 0;
}