红黑树 - 预购打印树
Red Black Tree - printing tree in preorder
本文关键字：打印 更新时间：2023-10-16
我已经基于Cormen制作了红黑树实现，但我一定破坏了一些东西，因为它不能正常工作。我相信我正确地重写了科尔门，但我不知道有什么问题......我怎么知道..我取了 10 个值并检查了树的外观 （http://secs.ceas.uc.edu/~franco/C321/html/RedBlack/redblack.html），我的看起来确实不同。所以我恳请任何可以帮助我找出问题的提示，整个代码很长，但没有它我无法重现错误，对此感到抱歉。我相信有罪的是插入后的旋转和/或修复......
编辑：新代码，但它仍然会导致红色甚至黑色违规，尽管我可以发誓我只是重写了伪代码以C++...
#include <cstdio>
#include <algorithm>
#include <string>
enum rbt_color { RED, BLACK };
struct rbt_node
{
int key; //klucz
int sub_tree; //wielkość poddrzewa
std::string data; //wartość (napis do 21 znaków)
rbt_node *left; //lewy syn
rbt_node *right; //prawy syn
rbt_node *parent;
rbt_color color; //kolor
};
int is_RED(rbt_node *root)
{
return root != NULL && root->color == RED;
}
int is_BLACK(rbt_node *root)
{
return root != NULL && root->color == BLACK;
}
rbt_node *make_node(int key, std::string data)
{
rbt_node *new_node = new rbt_node;
new_node->key = key;
new_node->data = data;
new_node->color = RED;
new_node->left = NULL;
new_node->right = NULL;
new_node->sub_tree = 1; //inicjalna wartość
return new_node;
}
void add_node(rbt_node *&tree, rbt_node *node, rbt_node *parent)
{
if(tree == NULL)
{
node->parent = parent;
tree = node;
}
else if(node->key < tree->key)
{
tree->sub_tree += 1;
add_node(tree->left, node, tree);
}
else if(node->key > tree->key)
{
tree->sub_tree += 1;
add_node(tree->right, node, tree);
}
}
//funkcja testująca drzewo, źródło http://www.eternallyconfuzzled.com/tuts/datastructures/jsw_tut_rbtree.aspx (trochę ulepszyłem)
int rbt_assert (rbt_node *root)
{
int lh, rh;
if ( root == NULL )
return 1;
else {
rbt_node *ln = root->left;
rbt_node *rn = root->right;
/* Consecutive RED links */
if ( is_RED ( root ) ) {
if ( is_RED ( ln ) || is_RED ( rn ) ) {
puts ( "RED violation" );
printf("VIOLATION AT KEY: %dn", root->key);
//return 0;
}
}
lh = rbt_assert ( ln );
rh = rbt_assert ( rn );
if (1 + (ln ? ln->sub_tree : 0) + (rn ? rn->sub_tree : 0) != root->sub_tree)
{
puts ("Subtree violation");
printf("VIOLATION AT KEY: %dn", root->key);
return 0;
}
if (root->left != NULL && root->left->parent != root || root->right != NULL && root->right->parent != root)
{
puts ("Parent violation");
printf("VIOLATION AT KEY: %dn", root->key);
return 0;
}
/* Invalid binary search tree */
if ( ( ln != NULL && ln->key >= root->key )
|| ( rn != NULL && rn->key <= root->key ) )
{
puts ( "Binary tree violation" );
return 0;
}
/* BLACK height mismatch */
if ( lh != 0 && rh != 0 && lh != rh ) {
puts ( "BLACK violation" );
return 0;
}
/* Only count BLACK links */
if ( lh != 0 && rh != 0 )
return is_RED ( root ) ? lh : lh + 1;
else
return 0;
}
}
void left_rotate(rbt_node *&root, rbt_node *&node)
{
rbt_node *new_node = node->right;
if(new_node != NULL)
{
node->right = new_node->left;
if(new_node->left != NULL)
new_node->left->parent = node;
if(node->parent == NULL)
root = new_node;
else if(node == node->parent->left)
node->parent->left = new_node;
else
node->parent->right = new_node;
new_node->left = node;
//aktualizujemy rozmiar poddrzewa
new_node->sub_tree = node->sub_tree;
node->sub_tree = 1;
if(node->left != NULL)
node->sub_tree += node->left->sub_tree;
if(node->right != NULL)
node->sub_tree += node->right->sub_tree;
new_node->parent = node->parent;
new_node->left->parent = new_node;
}
}
void right_rotate(rbt_node *&root, rbt_node *& node)
{
rbt_node *new_node = node->left;
if(new_node != NULL)
{
node->left = new_node->right;
if(new_node->right != NULL)
new_node->right->parent = node;
if(node->parent == NULL)
root = new_node;
else if(node == node->parent->right)
node->parent->right = new_node;
else
node->parent->left = new_node;
new_node->right = node;
//aktualizujemy rozmiar poddrzewa
new_node->sub_tree = node->sub_tree;
node->sub_tree = 1;
if(node->left != NULL)
node->sub_tree += node->left->sub_tree;
if(node->right != NULL)
node->sub_tree += node->right->sub_tree;
new_node->parent = node->parent;
new_node->right->parent = new_node;
}
}
void add_rbt_node(rbt_node *&root, int key, std::string data, rbt_node *parent)
{
rbt_node *element = make_node(key, data);
add_node(root, element, parent);
while(element != root && element->parent->color == RED)
{
if(element->parent == element->parent->parent->left)
{
rbt_node *uncle = element->parent->parent->right;
if(uncle != NULL && uncle->color == RED)
{
element->parent->color == BLACK;
uncle->color = BLACK;
element->parent->parent->color = RED;
element = element->parent->parent;
}
else
{
if(element == element->parent->right)
{
element = element->parent;
left_rotate(root, element);
}
element->parent->color = BLACK;
element->parent->parent->color = RED;
right_rotate(root, element->parent->parent);
}
}
else
{
rbt_node *uncle = element->parent->parent->left;
if(uncle != NULL && uncle->color == RED)
{
element->parent->color = BLACK;
uncle->color = BLACK;
element->parent->parent->color = RED;
element = element->parent->parent;
}
else
{
if(element == element->parent->left)
{
element = element->parent;
right_rotate(root, element);
}
element->parent->color = BLACK;
element->parent->parent->color = RED;
left_rotate(root, element->parent->parent);
}
}
}
root->color = BLACK;
}
void search_key(rbt_node *root, int key)
{
if(root == NULL)
printf("-n");
else if(root->key == key)
printf("%sn", root->data.c_str());
else if(root->key < key)
search_key(root->right, key);
else if(root->key > key)
search_key(root->left, key);
}
void min_key(rbt_node *root, int number)
{
if(root != NULL)
{
int rank = 1;
if(root->left != NULL)
rank += root->left->sub_tree;
if(rank == number)
printf("%sn", root->data.c_str());
else if(number < rank)
min_key(root->left, number);
else
min_key(root->right, number - rank);
}
}
void print_out(rbt_node *root)
{
if(root != NULL)
{
printf("%d %s ", root->key, root->data.c_str());
if(root->color == BLACK)
printf("black ");
else
printf("red ");
if(root->parent != NULL)
printf("%d ",root->parent->key);
else
printf("- ");
if(root->left != NULL)
printf("%d ",root->left->key);
else
printf("- ");
if(root->right != NULL)
printf("%d ",root->right->key);
else
printf("- ");
printf("n");
print_out(root->left);
if(root->right != NULL)
{
print_out(root->right);
}
}
}
int main()
{
int key;
char data [21];
char operation;
rbt_node *root = NULL;
while(scanf("%c",&operation) != EOF)
{
switch(operation)
{
case 'I':
scanf("%d",&key);
scanf("%s",data);
add_rbt_node(root, key, data, NULL);
break;
case 'S':
scanf("%d",&key);
search_key(root, key);
break;
case 'F':
scanf("%d",&key);
if(key <= root->sub_tree && key != 0)
min_key(root, key);
else
printf("-n");
break;
case 'G':
printf("%dn", rbt_assert(root));
break;
case 'P':
//print_out(root);
break;
}
}
}
一个问题是这一行（add_rbt_node的第 12 行）：
element->parent->color == BLACK;
几乎可以肯定的是：
element->parent->color = BLACK;
我已经确认解决此问题可以解决您在评论中强调的特定问题。如果您打开了所有警告，您的编译器可能会为您发现此问题。这是一个简单而明显的错误。
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