mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-27 14:14:24 +08:00
93c8332c83
This patch implements a union-find data structure in the kernel library, which includes operations for allocating nodes, freeing nodes, finding the root of a node, and merging two nodes. Signed-off-by: Xavier <xavier_qy@163.com> Signed-off-by: Tejun Heo <tj@kernel.org>
50 lines
1.1 KiB
C
50 lines
1.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/union_find.h>
|
|
|
|
/**
|
|
* uf_find - Find the root of a node and perform path compression
|
|
* @node: the node to find the root of
|
|
*
|
|
* This function returns the root of the node by following the parent
|
|
* pointers. It also performs path compression, making the tree shallower.
|
|
*
|
|
* Returns the root node of the set containing node.
|
|
*/
|
|
struct uf_node *uf_find(struct uf_node *node)
|
|
{
|
|
struct uf_node *parent;
|
|
|
|
while (node->parent != node) {
|
|
parent = node->parent;
|
|
node->parent = parent->parent;
|
|
node = parent;
|
|
}
|
|
return node;
|
|
}
|
|
|
|
/**
|
|
* uf_union - Merge two sets, using union by rank
|
|
* @node1: the first node
|
|
* @node2: the second node
|
|
*
|
|
* This function merges the sets containing node1 and node2, by comparing
|
|
* the ranks to keep the tree balanced.
|
|
*/
|
|
void uf_union(struct uf_node *node1, struct uf_node *node2)
|
|
{
|
|
struct uf_node *root1 = uf_find(node1);
|
|
struct uf_node *root2 = uf_find(node2);
|
|
|
|
if (root1 == root2)
|
|
return;
|
|
|
|
if (root1->rank < root2->rank) {
|
|
root1->parent = root2;
|
|
} else if (root1->rank > root2->rank) {
|
|
root2->parent = root1;
|
|
} else {
|
|
root2->parent = root1;
|
|
root1->rank++;
|
|
}
|
|
}
|