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添加注释和理解

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建峰 2024-06-28 11:32:53 +08:00
parent 0901b08417
commit e1763db190
1 changed files with 13 additions and 1 deletions
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14
src/tree.c
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@ -1188,33 +1188,46 @@ bool tree_rb_delete_fix(struct _tree* self, struct _tree_node* node)
brother = father->right; brother = father->right;
if(brother->color == RBT_RED) if(brother->color == RBT_RED)
{ {
// case 1
// father is black, brother is red
// brother has two black children
// so ...
brother->color = RBT_BLACK; brother->color = RBT_BLACK;
father->color = RBT_RED; father->color = RBT_RED;
tmp = tree_turn_left(self, father); tmp = tree_turn_left(self, father);
// After deleting the node, it became unbalanced
// so convert to case5
} }
else if(brother->right != NULL && brother->right->color == RBT_RED) else if(brother->right != NULL && brother->right->color == RBT_RED)
{ {
// case 2
brother->color = father->color; brother->color = father->color;
father->color = RBT_BLACK; father->color = RBT_BLACK;
brother->right->color = RBT_BLACK; brother->right->color = RBT_BLACK;
node = tree_turn_left(self, father); node = tree_turn_left(self, father);
// After deleting the node, it remains balanced
break; break;
} }
else if(brother->left != NULL && brother->left->color == RBT_RED) else if(brother->left != NULL && brother->left->color == RBT_RED)
{ {
// case 3
brother->color = RBT_RED; brother->color = RBT_RED;
brother->left->color = RBT_BLACK; brother->left->color = RBT_BLACK;
tmp = tree_turn_right(self, brother); tmp = tree_turn_right(self, brother);
// Convert to case2
} }
else else
{ {
// father is black, after delete node, total of black is -1
if(father->color = RBT_BLACK) if(father->color = RBT_BLACK)
{ {
// case 4
brother->color = RBT_RED; brother->color = RBT_RED;
node = father; node = father;
} }
else else
{ {
// case 5
brother->color = RBT_RED; brother->color = RBT_RED;
father->color = RBT_BLACK; father->color = RBT_BLACK;
break; break;
@ -1263,7 +1276,6 @@ bool tree_rb_delete_fix(struct _tree* self, struct _tree_node* node)
if(tmp != NULL && tmp->parent == NULL) if(tmp != NULL && tmp->parent == NULL)
{ {
self->_root = node; self->_root = node;
break;
} }
} }