python-binary-tree-traversal.py

from typing import Optional


class Node:
    def __init__(self, data):
        self.left: Optional[Node] = None
        self.right: Optional[Node] = None
        self.data = data

    def printTree(self):
        if self.left:
            self.left.printTree()

        print(self.data)

        if self.right:
            self.right.printTree()

    def insert(self, data):
        if self.data:
            if data < self.data:
                if self.left is None:
                    self.left = Node(data)
                else:
                    self.left.insert(data)
            elif data > self.data:
                if self.right is None:
                    self.right = Node(data)
                else:
                    self.right.insert(data)
        else:
            self.data = data

    def inorderTraversal(self, sub_root):
        res = []

        if sub_root:
            res = self.inorderTraversal(sub_root.left)
            res.append(sub_root.data)
            res = res + self.inorderTraversal(sub_root.right)

        return res

    def preorderTraversal(self, sub_root):
        res = []

        if sub_root:
            res.append(sub_root.data)
            res = res + self.preorderTraversal(sub_root.left)
            res = res + self.preorderTraversal(sub_root.right)

        return res

    def postorderTraversal(self, sub_root):
        res = []

        if sub_root:
            res = self.postorderTraversal(sub_root.left)
            res = res + self.postorderTraversal(sub_root.right)
            res.append(sub_root.data)

        return res


# Press the green button in the gutter to run the script.
if __name__ == '__main__':
    root = Node(27)
    root.insert(14)
    root.insert(35)
    root.insert(10)
    root.insert(19)
    root.insert(31)
    root.insert(42)
    print(root.inorderTraversal(root))
    print(root.preorderTraversal(root))
    print(root.postorderTraversal(root))