Grokking the Art of Recursion for Coding Interviews
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11. BST Inorder Traversal
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Problem Statement

Examples

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Problem Statement

Write Recursive Approach for Inorder Traversal of Binary Tree.

Given a binary tree, write a recursive algorithm to perform an inorder traversal of the tree and return the elements in the order they were visited.

Examples

Example 1:

Input:
           5
         /   \
        3     8
       / \   / \
      2   4 7   9

Output:
Inorder Traversal: [2, 3, 4, 5, 7, 8, 9]

Explanation:
The binary tree has the following structure:
           5
         /   \
        3     8
       / \   / \
      2   4 7   9

Performing an inorder traversal visits the nodes in ascending order: 2, 3, 4, 5, 7, 8, 9.

Example 2:

Input:
           10
         /    \
        6      15
       / \    / \
      3   8  12  18
            \
             9

Output:
Inorder Traversal: [3, 6, 8, 9, 10, 12, 15, 18]

Explanation:
The binary tree has the following structure:
           10
         /    \
        6      15
       / \    / \
      3   8  12  18
            \
             9

Performing an inorder traversal visits the nodes in ascending order: 3, 6, 8, 9, 10, 12, 15, 18.

Example 3:

Input:
           20
         /    \
        12     25
       / \    / \
      8   15  22  28
     / \       \
    6   10      24

Output:
Inorder Traversal: [6, 8, 10, 12, 15, 20, 22, 24, 25, 28]

Explanation:
The binary tree has the following structure:
           20
         /    \
        12     25
       / \    / \
      8   15  22  28
     / \       \
    6   10      24

Performing an inorder traversal visits the nodes in ascending order: 6, 8, 10, 12, 15, 20, 22, 24, 25, 28.

Constraints:

  • The number of nodes in the tree is in the range [0, 100].
  • -100 <= Node.val <= 100

Try it yourself

Try solving this question here:

Python3
Python3
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Problem Statement

Examples

Try it yourself