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#include "data_structure/union_find_tree.hpp"
頂点数 $N$ で辺数 $0$ の無向グラフ $G = (V, E)$ に対し、次が $O(\alpha(N))$ amortized (ただし $\alpha$ は Ackermann 関数の逆関数) で処理可能。
#pragma once
#include <vector>
/**
* @brief Union-Find Tree
* @docs data_structure/union_find_tree.md
* @note union-by-size + path-compression
*/
struct union_find_tree {
std::vector<int> data;
union_find_tree() = default;
explicit union_find_tree(std::size_t n) : data(n, -1) {}
bool is_root(int i) { return data[i] < 0; }
int find_root(int i) { return is_root(i) ? i : (data[i] = find_root(data[i])); }
int tree_size(int i) { return - data[find_root(i)]; }
int unite_trees(int i, int j) {
i = find_root(i); j = find_root(j);
if (i != j) {
if (tree_size(i) < tree_size(j)) std::swap(i, j);
data[i] += data[j];
data[j] = i;
}
return i;
}
bool is_same(int i, int j) { return find_root(i) == find_root(j); }
};
#line 2 "data_structure/union_find_tree.hpp"
#include <vector>
/**
* @brief Union-Find Tree
* @docs data_structure/union_find_tree.md
* @note union-by-size + path-compression
*/
struct union_find_tree {
std::vector<int> data;
union_find_tree() = default;
explicit union_find_tree(std::size_t n) : data(n, -1) {}
bool is_root(int i) { return data[i] < 0; }
int find_root(int i) { return is_root(i) ? i : (data[i] = find_root(data[i])); }
int tree_size(int i) { return - data[find_root(i)]; }
int unite_trees(int i, int j) {
i = find_root(i); j = find_root(j);
if (i != j) {
if (tree_size(i) < tree_size(j)) std::swap(i, j);
data[i] += data[j];
data[j] = i;
}
return i;
}
bool is_same(int i, int j) { return find_root(i) == find_root(j); }
};