1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/union_find.h>
3
4 /**
5 * uf_find - Find the root of a node and perform path compression
6 * @node: the node to find the root of
7 *
8 * This function returns the root of the node by following the parent
9 * pointers. It also performs path compression, making the tree shallower.
10 *
11 * Returns the root node of the set containing node.
12 */
13 struct uf_node *uf_find(struct uf_node *node)
14 {
15 struct uf_node *parent;
16
17 while (node->parent != node) {
18 parent = node->parent;
19 node->parent = parent->parent;
20 node = parent;
21 }
22 return node;
23 }
24
25 /**
26 * uf_union - Merge two sets, using union by rank
27 * @node1: the first node
28 * @node2: the second node
29 *
30 * This function merges the sets containing node1 and node2, by comparing
31 * the ranks to keep the tree balanced.
32 */
33 void uf_union(struct uf_node *node1, struct uf_node *node2)
34 {
35 struct uf_node *root1 = uf_find(node1);
36 struct uf_node *root2 = uf_find(node2);
37
38 if (root1 == root2)
39 return;
40
41 if (root1->rank < root2->rank) {
42 root1->parent = root2;
43 } else if (root1->rank > root2->rank) {
44 root2->parent = root1;
45 } else {
46 root2->parent = root1;
47 root1->rank++;
48 }
49 }
50
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