"""

GENERAL TREE

Data is stored in hierarchical form

ROOT --- Level 0

____________________|____________________

A B C --- Level 1

_____|_____ _____|_____ _____|_____

| | | | | | | | |

D E F G H I J K L --- Level 2

_____|_____ _____|_____

| | | | | |

M N O P Q R --- Level 3

Here, ROOT is "ROOT NODE" and A, B, C are "CHILD NODE"

> B-D-F-G is a sub-tree

> B is 'ROOT NODE' for F, G, H and G is 'ROOT NODE' for Q, R

> Those nodes [E, F, H, I, J, K, L...] who do not have any child node are "LEAF NODE"

> For (D, E), A will be Ancestor and for A, (D, E) would be Descendants

Tree is a recursive dta structure where a child node is another tree in itself

"""

class TreeNode:

""" Class TreeNode """

def __init__(self, data):

self.data = data

self.children = []

self.parent = None

def add_child(self, child):

""" Adds children elements to Tree """

child.parent = self # child is an instance of class(node)

# adding a child node to tree

self.children.append(child)

def get_level(self):

""" Gets the level of Tree by counting ancestors: if a node has no ancestor, it is root node """

level = 0 # initialised level to 0

p = self.parent

while p:

"""keep on going through parents and increasing levels"""

level += 1 # increase level by 1

p = p.parent

return level

def print_tree(self):

"""Display Tree in hierarchical format"""

spaces = ' ' * self.get_level() * 3 # printing 3 spaces for each level

prefix = spaces + "|__" if self.parent else ""

print(prefix + self.data) # prints prefix(probably spaces) based on level

# At leaf nodes, self.children will be an empty array... so we create a check if self.children() is an empty array or not

if self.children: # checks if len(self.children > 0)

for child in self.children:

child.print_tree() # It will recursively call this fn and print the sub-trees

def electronic_product():

root = TreeNode("Electronics")

laptop = TreeNode("Laptop")

laptop.add_child(TreeNode("Mac"))

laptop.add_child(TreeNode("Surface"))

laptop.add_child(TreeNode("Thinkpad"))

cellphones = TreeNode("cell Phone")

cellphones.add_child(TreeNode("iphone"))

cellphones.add_child(TreeNode("Samsung"))

cellphones.add_child(TreeNode("Vivo"))

tv = TreeNode("TV")

tv.add_child(TreeNode("Samsung"))

tv.add_child(TreeNode("MI"))

root.add_child(laptop)

root.add_child(cellphones)

root.add_child(tv)

# print(laptop.get_level()) # 1

# print(cellphones.get_level()) # 1

# print(tv.get_level()) # 1

return root

# main method

if __name__ == '__main__':

root = electronic_product()

root.print_tree() # prints tree in hierarchical format

# print(root.get_level()) # 0 // get level of root node