From 93c8332c8373fee415bd79f08d5ba4ba7ca5ad15 Mon Sep 17 00:00:00 2001 From: Xavier Date: Thu, 4 Jul 2024 14:24:43 +0800 Subject: Union-Find: add a new module in kernel library 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 Signed-off-by: Tejun Heo --- lib/union_find.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 lib/union_find.c (limited to 'lib/union_find.c') diff --git a/lib/union_find.c b/lib/union_find.c new file mode 100644 index 000000000000..413b0f8adf7a --- /dev/null +++ b/lib/union_find.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +/** + * 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++; + } +} -- cgit v1.2.3