#line 1 "test/aoj/GRL_5_C/main.hld.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_5_C"
#include <iostream>
#line 3 "Mylib/Graph/Template/graph.cpp"
#include <vector>
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 2 "Mylib/Graph/TreeUtils/lca_hld.cpp"
#include <utility>
#line 5 "Mylib/Graph/TreeUtils/lca_hld.cpp"
namespace haar_lib {
template <typename T>
class lowest_common_ancestor_hld {
int n_;
std::vector<int> sub_, par_, head_, id_;
int dfs_sub(int cur, int p, tree<T> &tr) {
par_[cur] = p;
int t = 0;
for (auto &e : tr[cur]) {
if (e.to == p) continue;
sub_[cur] += dfs_sub(e.to, cur, tr);
if (sub_[e.to] > t) {
t = sub_[e.to];
std::swap(e, tr[cur][0]);
}
}
return sub_[cur];
}
void dfs_build(int cur, int &i, tree<T> &tr) {
id_[cur] = i;
++i;
for (auto &e : tr[cur]) {
if (e.to == par_[cur]) continue;
head_[e.to] = (e.to == tr[cur][0].to ? head_[cur] : e.to);
dfs_build(e.to, i, tr);
}
}
public:
lowest_common_ancestor_hld() {}
lowest_common_ancestor_hld(tree<T> tr, int root) : n_(tr.size()), sub_(n_, 1), par_(n_, -1), head_(n_), id_(n_) {
dfs_sub(root, -1, tr);
int i = 0;
dfs_build(root, i, tr);
}
int lca(int u, int v) const {
while (1) {
if (id_[u] > id_[v]) std::swap(u, v);
if (head_[u] == head_[v]) return u;
v = par_[head_[v]];
}
}
int operator()(int u, int v) const { return lca(u, v); }
T distance(int u, int v, const std::vector<T> &dist) const {
return dist[u] + dist[v] - 2 * dist[lca(u, v)];
}
};
} // namespace haar_lib
#line 2 "Mylib/IO/input_tuples.cpp"
#include <initializer_list>
#line 4 "Mylib/IO/input_tuples.cpp"
#include <tuple>
#line 6 "Mylib/IO/input_tuple.cpp"
namespace haar_lib {
template <typename T, size_t... I>
static void input_tuple_helper(std::istream &s, T &val, std::index_sequence<I...>) {
(void) std::initializer_list<int>{(void(s >> std::get<I>(val)), 0)...};
}
template <typename T, typename U>
std::istream &operator>>(std::istream &s, std::pair<T, U> &value) {
s >> value.first >> value.second;
return s;
}
template <typename... Args>
std::istream &operator>>(std::istream &s, std::tuple<Args...> &value) {
input_tuple_helper(s, value, std::make_index_sequence<sizeof...(Args)>());
return s;
}
} // namespace haar_lib
#line 8 "Mylib/IO/input_tuples.cpp"
namespace haar_lib {
template <typename... Args>
class InputTuples {
struct iter {
using value_type = std::tuple<Args...>;
value_type value;
bool fetched = false;
int N, c = 0;
value_type operator*() {
if (not fetched) {
std::cin >> value;
}
return value;
}
void operator++() {
++c;
fetched = false;
}
bool operator!=(iter &) const {
return c < N;
}
iter(int N) : N(N) {}
};
int N;
public:
InputTuples(int N) : N(N) {}
iter begin() const { return iter(N); }
iter end() const { return iter(N); }
};
template <typename... Args>
auto input_tuples(int N) {
return InputTuples<Args...>(N);
}
} // namespace haar_lib
#line 8 "Mylib/IO/input_tuples_with_index.cpp"
namespace haar_lib {
template <typename... Args>
class InputTuplesWithIndex {
struct iter {
using value_type = std::tuple<int, Args...>;
value_type value;
bool fetched = false;
int N;
int c = 0;
value_type operator*() {
if (not fetched) {
std::tuple<Args...> temp;
std::cin >> temp;
value = std::tuple_cat(std::make_tuple(c), temp);
}
return value;
}
void operator++() {
++c;
fetched = false;
}
bool operator!=(iter &) const {
return c < N;
}
iter(int N) : N(N) {}
};
int N;
public:
InputTuplesWithIndex(int N) : N(N) {}
iter begin() const { return iter(N); }
iter end() const { return iter(N); }
};
template <typename... Args>
auto input_tuples_with_index(int N) {
return InputTuplesWithIndex<Args...>(N);
}
} // namespace haar_lib
#line 8 "test/aoj/GRL_5_C/main.hld.test.cpp"
namespace hl = haar_lib;
int main() {
int n;
std::cin >> n;
hl::tree<int> tree(n);
for (auto [i, k] : hl::input_tuples_with_index<int>(n)) {
for (auto [c] : hl::input_tuples<int>(k)) {
tree.add_edge(i, c, 1);
}
}
auto lca = hl::lowest_common_ancestor_hld(tree, 0);
int q;
std::cin >> q;
for (auto [u, v] : hl::input_tuples<int, int>(q)) {
std::cout << lca(u, v) << std::endl;
}
return 0;
}
test/aoj/GRL_5_C/main.hld.test.cpp
Basic graph
(Mylib/Graph/Template/graph.cpp)