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/* SPDX-License-Identifier: Apache-2.0
* Copyright 2011-2022 Blender Foundation */
#ifndef __UTIL_DISJOINT_SET_H__
#define __UTIL_DISJOINT_SET_H__
#include "util/array.h"
#include <utility>
CCL_NAMESPACE_BEGIN
class DisjointSet {
private:
array<size_t> parents;
array<size_t> ranks;
public:
DisjointSet(size_t size) : parents(size), ranks(size)
{
for (size_t i = 0; i < size; i++) {
parents[i] = i;
ranks[i] = 0;
}
}
size_t find(size_t x)
{
size_t root = x;
while (parents[root] != root) {
root = parents[root];
}
while (parents[x] != root) {
size_t parent = parents[x];
parents[x] = root;
x = parent;
}
return root;
}
void join(size_t x, size_t y)
{
size_t x_root = find(x);
size_t y_root = find(y);
if (x_root == y_root) {
return;
}
if (ranks[x_root] < ranks[y_root]) {
std::swap(x_root, y_root);
}
parents[y_root] = x_root;
if (ranks[x_root] == ranks[y_root]) {
ranks[x_root]++;
}
}
};
CCL_NAMESPACE_END
#endif /* __UTIL_DISJOINT_SET_H__ */
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