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In rbrepair, re-color the root or the first non-block node we find to

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be black.  Re-coloring the root is probably not needed but won't hurt.
This commit is contained in:
Todd C. Miller
2009-06-29 13:36:20 +00:00
parent 4764730f79
commit 02dd5d998d
1 changed files with 11 additions and 9 deletions
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20
redblack.c
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2004-2005, 2007 Todd C. Miller <Todd.Miller@courtesan.com>
* Copyright (c) 2004-2005, 2007,2009 Todd C. Miller <Todd.Miller@courtesan.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@@ -77,10 +77,11 @@ static void _rbdestroy __P((struct rbtree *, struct rbnode *,
* In addition to the ordinary requirements imposed on binary search
* trees, we make the following additional requirements of any valid
* red-black tree:
* 1) The root is black.
* 2) All leaves are black.
* 3) Both children of each red node are black.
* 4) The paths from each leaf up to the root each contain the same
* 1) Every node is either red or black.
* 2) The root is black.
* 3) All leaves are black.
* 4) Both children of each red node are black.
* 5) The paths from each leaf up to the root each contain the same
* number of black nodes.
*/
@@ -372,8 +373,8 @@ rbdestroy(tree, destroy)
* Delete node 'z' from the tree and return its data pointer.
*/
void *rbdelete(tree, z)
struct rbtree* tree;
struct rbnode* z;
struct rbtree *tree;
struct rbnode *z;
{
struct rbnode *x, *y;
void *data = z->data;
@@ -444,7 +445,7 @@ rbrepair(tree, node)
node->parent->color = black;
sibling->right->color = black;
rotate_left(tree, node->parent);
break;
node = rbroot(tree); /* exit loop */
}
} else { /* if (node == node->parent->right) */
sibling = node->parent->left;
@@ -468,8 +469,9 @@ rbrepair(tree, node)
node->parent->color = black;
sibling->left->color = black;
rotate_right(tree, node->parent);
break;
node = rbroot(tree); /* exit loop */
}
}
}
node->color = black;
}