#line 1 "test/aoj/GRL_5_C/main.doubling.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_doubling.cpp"
#include <cmath>
#line 5 "Mylib/Graph/TreeUtils/lca_doubling.cpp"
namespace haar_lib {
template <typename T>
class lowest_common_ancestor_doubling {
int n_, log2n_;
std::vector<std::vector<int>> parent_;
std::vector<int> depth_;
void dfs(const tree<T> &tr, int cur, int par, int d) {
parent_[cur][0] = par;
depth_[cur] = d;
for (auto &e : tr[cur]) {
if (e.to != par) {
dfs(tr, e.to, cur, d + 1);
}
}
}
public:
lowest_common_ancestor_doubling() {}
lowest_common_ancestor_doubling(const tree<T> &tr, int root) : n_(tr.size()), log2n_((int) ceil(log2(n_)) + 1), parent_(n_, std::vector<int>(log2n_)), depth_(n_) {
dfs(tr, root, -1, 0);
for (int k = 0; k < log2n_ - 1; ++k) {
for (int v = 0; v < n_; ++v) {
if (parent_[v][k] == -1)
parent_[v][k + 1] = -1;
else
parent_[v][k + 1] = parent_[parent_[v][k]][k];
}
}
}
int lca(int a, int b) const {
if (depth_[a] >= depth_[b]) std::swap(a, b);
for (int k = 0; k < log2n_; ++k) {
if ((depth_[b] - depth_[a]) >> k & 1) b = parent_[b][k];
}
if (a == b) return a;
for (int k = log2n_; --k >= 0;) {
if (parent_[a][k] != parent_[b][k]) {
a = parent_[a][k];
b = parent_[b][k];
}
}
return parent_[a][0];
}
int operator()(int a, int b) const { return lca(a, b); }
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>
#include <utility>
#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.doubling.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_doubling(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.doubling.test.cpp
Basic graph
(Mylib/Graph/Template/graph.cpp)