#line 1 "test/aoj/GRL_2_A/main.kruskal.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_2_A"
#include <iostream>
#line 2 "Mylib/Graph/MinimumSpanningTree/kruskal.cpp"
#include <algorithm>
#include <vector>
#line 3 "Mylib/DataStructure/UnionFind/unionfind.cpp"
#include <numeric>
#line 5 "Mylib/DataStructure/UnionFind/unionfind.cpp"
namespace haar_lib {
class unionfind {
int n_, count_;
mutable std::vector<int> parent_;
std::vector<int> depth_, size_;
public:
unionfind() {}
unionfind(int n) : n_(n), count_(n), parent_(n), depth_(n, 1), size_(n, 1) {
std::iota(parent_.begin(), parent_.end(), 0);
}
int root_of(int i) const {
if (parent_[i] == i)
return i;
else
return parent_[i] = root_of(parent_[i]);
}
bool is_same(int i, int j) const { return root_of(i) == root_of(j); }
int merge(int i, int j) {
const int ri = root_of(i), rj = root_of(j);
if (ri == rj)
return ri;
else {
--count_;
if (depth_[ri] < depth_[rj]) {
parent_[ri] = rj;
size_[rj] += size_[ri];
return rj;
} else {
parent_[rj] = ri;
size_[ri] += size_[rj];
if (depth_[ri] == depth_[rj]) ++depth_[ri];
return ri;
}
}
}
int size_of(int i) const { return size_[root_of(i)]; }
int count_groups() const { return count_; }
auto get_groups() const {
std::vector<std::vector<int>> ret(n_);
for (int i = 0; i < n_; ++i) {
ret[root_of(i)].push_back(i);
}
ret.erase(
std::remove_if(
ret.begin(), ret.end(),
[](const auto &a) { return a.empty(); }),
ret.end());
return ret;
}
};
} // namespace haar_lib
#line 4 "Mylib/Graph/Template/graph.cpp"
namespace haar_lib {
template <typename T>
struct edge {
int from, to;
T cost;
int index = -1;
edge() {}
edge(int from, int to, T cost) : from(from), to(to), cost(cost) {}
edge(int from, int to, T cost, int index) : from(from), to(to), cost(cost), index(index) {}
};
template <typename T>
struct graph {
using weight_type = T;
using edge_type = edge<T>;
std::vector<std::vector<edge<T>>> data;
auto& operator[](size_t i) { return data[i]; }
const auto& operator[](size_t i) const { return data[i]; }
auto begin() const { return data.begin(); }
auto end() const { return data.end(); }
graph() {}
graph(int N) : data(N) {}
bool empty() const { return data.empty(); }
int size() const { return data.size(); }
void add_edge(int i, int j, T w, int index = -1) {
data[i].emplace_back(i, j, w, index);
}
void add_undirected(int i, int j, T w, int index = -1) {
add_edge(i, j, w, index);
add_edge(j, i, w, index);
}
template <size_t I, bool DIRECTED = true, bool WEIGHTED = true>
void read(int M) {
for (int i = 0; i < M; ++i) {
int u, v;
std::cin >> u >> v;
u -= I;
v -= I;
T w = 1;
if (WEIGHTED) std::cin >> w;
if (DIRECTED)
add_edge(u, v, w, i);
else
add_undirected(u, v, w, i);
}
}
};
template <typename T>
using tree = graph<T>;
} // namespace haar_lib
#line 6 "Mylib/Graph/MinimumSpanningTree/kruskal.cpp"
namespace haar_lib {
template <typename T>
std::vector<edge<T>> kruskal(const graph<T> &graph) {
const int n = graph.size();
std::vector<edge<T>> edges;
for (auto &v : graph) {
for (auto &e : v) {
edges.push_back(e);
}
}
std::sort(
edges.begin(), edges.end(),
[](const auto &a, const auto &b) { return a.cost < b.cost; });
unionfind uf(n);
std::vector<edge<T>> ret;
for (auto &e : edges) {
if (not uf.is_same(e.from, e.to)) {
uf.merge(e.from, e.to);
ret.push_back(e);
}
}
return ret;
}
} // namespace haar_lib
#line 6 "test/aoj/GRL_2_A/main.kruskal.test.cpp"
namespace hl = haar_lib;
int main() {
int V, E;
std::cin >> V >> E;
hl::graph<int64_t> g(V);
g.read<0, false>(E);
auto res = hl::kruskal(g);
int64_t ans = 0;
for (auto &e : res) ans += e.cost;
std::cout << ans << std::endl;
return 0;
}
test/aoj/GRL_2_A/main.kruskal.test.cpp
Union-find
(Mylib/DataStructure/UnionFind/unionfind.cpp)