Maximum Depth of Binary Tree Easy 0 attempts
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Maximum Depth of Binary Tree

Easy TreeBinary TreeDFS LeetCode

Given the root of a binary tree, return its maximum depth. A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Example 1:

Input: root = [3,9,20,null,null,15,7]
Output: 3

Example 2:

Input: root = [1,null,2]
Output: 2
Sample Input
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Sample Output
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Constraints
  • 0 <= number of nodes <= 10^4
  • -100 <= Node.val <= 100
Test Cases
Case 1
Args: [[3,9,20,null,null,15,7]] Expected: 3
Case 2
Args: [[1,null,2]] Expected: 2
Case 3
Args: [[]] Expected: 0
Topics
TreeBinary TreeDFS

Approach: Recursive DFS

The depth of a tree is 1 plus the maximum of the depths of its left and right subtrees. Base case: a null node has depth 0.

function maximumDepthOfBinaryTree(root) {
  if (!root) return 0;
  return 1 + Math.max(
    maximumDepthOfBinaryTree(root.left),
    maximumDepthOfBinaryTree(root.right)
  );
}

Time Complexity: O(n)

Space Complexity: O(h) where h is tree height

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