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Build Binary Tree from Preorder and Inorder Traversal

Explore how to construct a binary tree from given preorder and inorder traversal arrays. Understand the relationship between these traversals and implement the solution to reconstruct the tree accurately.

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Statement

Create a binary tree from two integer arrays, p_order and i_order, where p_order represents a preorder traversal of a binary tree, and i_order represents an inorder traversal of the same tree.

Constraints:

  • 1≤1 \leq p_order.length, i_order.length ≤1000\leq1000
  • i_order.length ==== p_order.length
  • −1000≤-1000 \leq p_order[i], i_order[i] ≤1000\leq 1000
  • p_order and i_order consist of unique values.
  • Each value of i_order also appears in p_order and vice versa.

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps us to check if you’re solving the correct problem:

Build Binary Tree from Preorder and Inorder Traversal

1.

Select the correct binary tree constructed from preorder and inorder traversal:

preorder = [1, 12, 15, 6, 9, 5, 2]

inorder = [15, 12, 6, 1, 5, 9, 2]

A.
    1
   /  \
  12   9
 / \  / \
15  6 5  2
B.
    12
   /  \
  1    9
 / \  / \
15  6 5  2
C.
    15
   /  \
  12   9
 / \  / \
1  6 5   2
D.
    9
   /  \
  1   12
 / \  / \
15  6 5  2
1 / 2

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5

Try it yourself

Implement your solution in the following coding playground.

Python
usercode > main.py
# Definition of a binary tree node

#

# class TreeNode:

#     def __init__(self, data):

#         self.data = data

#         self.left = None

#         self.right = None



from ds_v1.BinaryTree.BinaryTree import TreeNode



def build_tree(p_order, i_order):



    # Replace this placeholder return statement with your code

    return TreeNode(-1)
Build Binary Tree from Preorder and Inorder Traversal