When it is required to construct a binary tree, and perform operations such as inserting an element, deleting an element and displaying elements of the tree, a class is defined with methods in it. An instance of the class is defined and this is used to access the elements and perform operations.
Below is a demonstration of the same −
class Tree_struct: def __init__(self, data=None, parent=None): self.key = data self.children =  self.parent = parent def set_root(self, data): self.key = data def add_node(self, node): self.children.append(node) def search_node(self, key): if self.key == key: return self for child in self.children: temp = child.search_node(key) if temp is not None: return temp return None def remove_node(self): parent = self.parent index = parent.children.index(self) parent.children.remove(self) for child in reversed(self.children): parent.children.insert(index, child) child.parent = parent def bfs(self): queue = [self] while queue != : popped = queue.pop(0) for child in popped.children: queue.append(child) print(popped.key, end=' ') my_instance = None print('Menu (this assumes no duplicate keys)') print('add <data> at root') print('add <data> below <data>') print('remove <data>') print('display') print('quit') while True: do = input('What would you like to do? ').split() operation = do.strip().lower() if operation == 'add': data = int(do) new_node = Tree_struct(data) suboperation = do.strip().lower() if suboperation == 'at': my_instance = new_node elif suboperation == 'below': position = do.strip().lower() key = int(position) ref_node = None if my_instance is not None: ref_node = my_instance.search_node(key) if ref_node is None: print('No such key.') continue new_node.parent = ref_node ref_node.add_node(new_node) elif operation == 'remove': data = int(do) to_remove = my_instance.search_node(data) if my_instance == to_remove: if my_instance.children == : my_instance = None else: leaf = my_instance.children while leaf.children != : leaf = leaf.children leaf.parent.children.remove_node(leaf) leaf.parent = None leaf.children = my_instance.children my_instance = leaf else: to_remove.remove_node() elif operation == 'display': if my_instance is not None: print('Breadth First Search traversal is : ', end='') my_instance.bfs() print() else: print('The tree is empty') elif operation == 'quit': break
Menu (this assumes no duplicate keys) add <data> at root add <data> below <data> remove <data> display quit What would you like to do? add 5 at root What would you like to do? add 6 below 5 What would you like to do? add 8 below 6 What would you like to do? remove 8 What would you like to do? display Breadth First Search traversal is : 5 6 What would you like to do? quit
The ‘Tree_struct’ class with required attributes is created.
It has an ‘init’ function that is used to create an empty list.
Another method named ‘set_root’ is defined to specify the root of the tree.
Another method named ‘add_node’ is defined that helps add nodes to the tree.
Another method named ‘search_node’ is defined that helps search for a specific element.
A method named ‘remove_node’ is defined, that deletes elements from the tree.
Another method named ‘bfs’ is defined, that helps perform breadth first search on the tree.
An instance is created and assigned to ‘None’.
The user input is taken for the operation that needs to be performed.
Depending on the user’ choice, the operation is performed.
Relevant output is displayed on the console.