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RedBlackTree.py
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RedBlackTree.py
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import Node_class
class RedBlackTree:
def __init__(self, root=None):
self.root = root
self.size = 0
self.black_node_count = 0
def create_tree(self, ptr, e):
node = Node_class.Node(e)
if self.root is None:
self.root = node
self.root.node_black_color = True
self.size += 1
return self.root
else:
if e == ptr.node_value:
print(f'Element {e} is already in the tree!')
return
if e > ptr.node_value:
if ptr.node_right_tree is None:
ptr.node_right_tree = node
node.node_parent = ptr
node.is_left_child = False
self.check_color(node)
self.size += 1
return node
else:
while ptr.node_right_tree is not None:
ptr = ptr.node_right_tree
ptr.node_right_tree = node
node.node_parent = ptr
node.is_left_child = False
self.check_color(node)
self.size += 1
return node
else:
if ptr.node_left_tree is None:
ptr.node_left_tree = node
node.node_parent = ptr
node.is_left_child = True
self.check_color(node)
self.size += 1
return node
else:
while ptr.node_left_tree is not None:
ptr = ptr.node_left_tree
ptr.node_left_tree = node
node.node_parent = ptr
node.is_left_child = True
self.check_color(node)
self.size += 1
return node
def check_color(self, ptr) -> 'ptr is node':
if ptr is self.root:
self.root.node_black_color = True
return
else:
if ptr.node_black_color is False and ptr.node_parent.node_black_color is False:
# print(f'{ptr.node_value} is Red and its parent {ptr.node_parent.node_value} is Red')
# print(f'correcting the tree...')
self.correct_tree(ptr)
self.check_color(ptr.node_parent)
def correct_tree(self, ptr):
if ptr.node_parent.is_left_child:
if ptr.node_parent.node_parent.node_right_tree is None \
or ptr.node_parent.node_parent.node_right_tree.node_black_color is True:
# print('parent_parent_right_tree is None or parent_parent_right_tree_color is Black')
# print('doing rotation...')
return self.rotate(ptr)
if ptr.node_parent.node_parent.node_right_tree is not None:
# print('doing recoloring')
ptr.node_parent.node_parent.node_right_tree.node_black_color = True
ptr.node_parent.node_parent.node_black_color = False
ptr.node_parent.node_black_color = True
return
else:
if ptr.node_parent.node_parent.node_left_tree is None \
or ptr.node_parent.node_parent.node_left_tree.node_black_color is True:
# print('parent_parent_left_tree is None or parent_parent_left_tree_color is Black')
# print('doing rotation...')
return self.rotate(ptr)
if ptr.node_parent.node_parent.node_left_tree is not None:
# print('doing recoloring')
ptr.node_parent.node_parent.node_left_tree.node_black_color = True
ptr.node_parent.node_parent.node_black_color = False
ptr.node_parent.node_black_color = True
return
def rotate(self, ptr):
if ptr.is_left_child:
if ptr.node_parent.is_left_child:
self.left_rotation(ptr.node_parent.node_parent)
ptr.node_black_color = False
ptr.node_parent.node_black_color = True
if ptr.node_parent.node_right_tree is not None:
ptr.node_parent.node_right_tree.node_black_color = False
return
else:
self.right_left_rotation(ptr.node_parent.node_parent)
ptr.node_black_color = True
ptr.node_right_tree.node_black_color = False
ptr.node_left_tree.node_black_color = False
return
else:
if ptr.is_left_child is False:
if ptr.node_parent.is_left_child is False:
self.right_rotation(ptr.node_parent.node_parent)
ptr.node_black_color = False
ptr.node_parent.node_black_color = True
if ptr.node_parent.node_left_tree is not None:
ptr.node_parent.node_left_tree.node_black_color = False
return
else:
self.left_right_rotation(ptr.node_parent.node_parent)
ptr.node_black_color = True
ptr.node_left_tree.node_black_color = False
ptr.node_right_tree.node_black_color = False
return
def left_rotation(self, ptr):
# print('doing left rotation')
temp = ptr.node_left_tree
ptr.node_left_tree = temp.node_right_tree
if temp.node_right_tree is None:
temp.node_right_tree = ptr
else:
ptr.node_left_tree.node_parent = ptr
temp.node_right_tree = ptr
ptr.node_left_tree.is_left_child = True
if ptr.node_parent is None:
temp.node_parent = None
ptr.node_parent = temp
temp.is_left_child = False
self.root = temp
return temp
else:
if ptr.is_left_child:
temp.node_parent = ptr.node_parent
temp.node_parent.node_left_tree = temp
temp.is_left_child = True
ptr.is_left_child = False
ptr.node_parent = temp
return temp
else:
temp.node_parent = ptr.node_parent
temp.node_parent.node_right_tree = temp
temp.is_left_child = False
ptr.is_left_child = False
ptr.node_parent = temp
return temp
def right_rotation(self, ptr):
# print('doing right rotation')
temp = ptr.node_right_tree
ptr.node_right_tree = temp.node_left_tree
if temp.node_left_tree is None:
temp.node_left_tree = ptr
else:
ptr.node_right_tree.node_parent = ptr
temp.node_left_tree = ptr
ptr.node_right_tree.is_left_child = False
if ptr.node_parent is None:
temp.node_parent = None
ptr.node_parent = temp
temp.is_left_child = False
self.root = temp
ptr.is_left_child = True
return temp
else:
if ptr.is_left_child:
temp.node_parent = ptr.node_parent
temp.node_parent.node_left_tree = temp
temp.is_left_child = True
ptr.is_left_child = True
ptr.node_parent = temp
return temp
else:
temp.node_parent = ptr.node_parent
temp.node_parent.node_right_tree = temp
temp.is_left_child = False
ptr.is_left_child = True
ptr.node_parent = temp
return temp
def left_right_rotation(self, ptr):
# print('doing left-right rotation')
temp_p = ptr.node_left_tree
temp_c = temp_p.node_right_tree
ptr.node_left_tree = temp_c.node_right_tree
temp_p.node_right_tree = temp_c.node_left_tree
if ptr.node_left_tree is None:
temp_c.node_right_tree = ptr
else:
ptr.node_left_tree.node_parent = ptr
temp_c.node_right_tree = ptr
ptr.node_left_tree.is_left_child = True
if temp_p.node_right_tree is None:
temp_c.node_left_tree = temp_p
temp_p.node_parent = temp_c
else:
temp_p.node_right_tree.node_parent = temp_p
temp_c.node_left_tree = temp_p
temp_p.node_parent = temp_c
temp_p.is_left_child = True
temp_p.node_right_tree.is_left_child = False
if ptr.node_parent is None:
ptr.node_parent = temp_c
self.root = temp_c
temp_c.node_parent = None
ptr.is_left_child = False
return temp_c
else:
if ptr.is_left_child:
temp_c.node_parent = ptr.node_parent
temp_c.node_parent.node_left_tree = temp_c
temp_c.is_left_child = True
ptr.node_parent = temp_c
ptr.is_left_child = False
return temp_c
else:
temp_c.node_parent = ptr.node_parent
temp_c.node_parent.node_right_tree = temp_c
temp_c.is_left_child = False
ptr.node_parent = temp_c
ptr.is_left_child = False
return temp_c
def right_left_rotation(self, ptr):
# print('doing right-left rotation')
temp_p = ptr.node_right_tree
temp_c = temp_p.node_left_tree
ptr.node_right_tree = temp_c.node_left_tree
temp_p.node_left_tree = temp_c.node_right_tree
if ptr.node_right_tree is None:
temp_c.node_left_tree = ptr
else:
ptr.node_right_tree.node_parent = ptr
temp_c.node_left_tree = ptr
ptr.node_right_tree.is_left_child = False
temp_c.node_left_tree.is_left_child = True
if temp_p.node_left_tree is None:
temp_c.node_right_tree = temp_p
temp_p.node_parent = temp_c
else:
temp_p.node_left_tree.node_parent = temp_p
temp_c.node_right_tree = temp_p
temp_p.node_parent = temp_c
temp_p.is_left_child = False
temp_p.node_left_tree.is_left_child = True
if ptr.node_parent is None:
ptr.node_parent = temp_c
self.root = temp_c
ptr.is_left_child = True
temp_c.is_left_child = False
temp_c.node_parent = None
return temp_c
else:
if ptr.is_left_child:
temp_c.node_parent = ptr.node_parent
temp_c.node_parent.node_left_tree = temp_c
temp_c.is_left_child = True
ptr.node_parent = temp_c
ptr.is_left_child = True
return temp_c
else:
temp_c.node_parent = ptr.node_parent
temp_c.node_parent.node_right_tree = temp_c
temp_c.is_left_child = False
ptr.node_parent = temp_c
ptr.is_left_child = True
return temp_c
def find_element(self, ptr, e):
if ptr is not None:
if e == ptr.node_value:
print()
print(f"""Element {e} is found in the tree!""")
return True
elif e < ptr.node_value:
self.find_element(ptr.node_left_tree, e)
else:
self.find_element(ptr.node_right_tree, e)
else:
print()
print(f"""Element {e} is {'not found'.upper()} in the tree""")
return False
def remove_element(self, ptr, e):
if ptr is None:
# print(f"""Element {e} is {'not'.upper()} found in the tree""")
return ptr
else:
if ptr.node_left_tree is not None:
ptr.node_left_tree = self.remove_element(ptr.node_left_tree, e)
if ptr.node_value == e:
temp = ptr.node_parent
if ptr.node_left_tree is None and ptr.node_right_tree is None:
ptr.node_parent = None
if temp is None:
ptr = temp
self.root = ptr
print(f"""Element {e} was deleted from the tree""")
return ptr
else:
if ptr.is_left_child:
temp.node_left_tree = None
print(f"""Element {e} was deleted from the tree""")
ptr = temp.node_left_tree
self.check_color(temp)
return ptr
else:
temp.node_right_tree = None
print(f"""Element {e} was deleted from the tree""")
ptr = temp.node_right_tree
self.check_color(temp)
return ptr
elif ptr.node_left_tree is not None and ptr.node_right_tree is None:
ptr.node_left_tree.node_parent = temp
if temp is None:
temp_root = ptr.node_left_tree
ptr.node_left_tree = None
self.root = temp_root
print(f"""Element {e} was deleted from the tree""")
self.check_color(temp_root)
return temp_root
else:
if ptr.is_left_child:
ptr.node_parent = None
temp.node_left_tree = ptr.node_left_tree
ptr.node_left_tree = None
print(f"""Element {e} was deleted from the tree""")
self.check_color(temp.node_left_tree)
return temp.node_left_tree
else:
ptr.node_parent = None
temp.node_right_tree = ptr.node_left_tree
ptr.node_left_tree = None
print(f"""Element {e} was deleted from the tree""")
self.check_color(temp.node_right_tree)
return temp.node_right_tree
elif ptr.node_left_tree is None and ptr.node_right_tree is not None:
ptr.node_right_tree.node_parent = temp
if temp is None:
temp_root = ptr.node_right_tree
ptr.node_right_tree = None
self.root = temp_root
print(f"""Element {e} was deleted from the tree""")
self.check_color(temp_root)
return temp_root
else:
if ptr.is_left_child:
ptr.node_parent = None
temp.node_left_tree = ptr.node_right_tree
ptr.node_right_tree = None
print(f"""Element {e} was deleted from the tree""")
self.check_color(temp.node_left_tree)
return temp.node_left_tree
else:
ptr.node_parent = None
temp.node_right_tree = ptr.node_right_tree
ptr.node_right_tree = None
print(f"""Element {e} was deleted from the tree""")
self.check_color(temp.node_right_tree)
return temp.node_right_tree
elif ptr.node_left_tree is not None and ptr.node_right_tree is not None:
temp = self.find_greatest(ptr.node_left_tree)
ptr.node_value, temp.node_value = temp.node_value, ptr.node_value
ptr.node_left_tree = self.remove_element(ptr.node_left_tree, e)
if ptr.node_right_tree is not None:
ptr.node_right_tree = self.remove_element(ptr.node_right_tree, e)
return ptr
def find_greatest(self, ptr):
if ptr is None:
return None
else:
if ptr.node_right_tree is not None:
return self.find_greatest(ptr.node_right_tree)
return ptr
def height_of_tree(self, ptr):
if ptr is None:
return 0
else:
height_left_tree = 1 + self.height_of_tree(ptr.node_left_tree)
height_right_tree = 1 + self.height_of_tree(ptr.node_right_tree)
return max(height_left_tree, height_right_tree)
def final_height(self):
if self.root is None:
return 0
height = (self.height_of_tree(self.root)) - 1
print('The height of the tree is', height)
return height
def number_of_black_nodes(self, ptr):
if ptr is None:
return 1
self.number_of_black_nodes(ptr.node_left_tree)
self.number_of_black_nodes(ptr.node_right_tree)
if ptr.node_black_color:
self.black_node_count += 1
return self.black_node_count
def number_of_nodes_in_tree(self):
if self.root is None:
return 0
else:
print(f'Size of tree is {self.size}')
return self.size
def display_in_order(self, ptr):
if ptr is not None:
self.display_in_order(ptr.node_left_tree)
print(ptr.node_value, ptr.node_black_color, end='\n')
self.display_in_order(ptr.node_right_tree)