[Leetcode] 104. Maximum Depth of Binary Tree

Debakar Roy included in Programming Algorithms LeetCode

2019-07-23 166 words One minute

Contents

Maximum Depth of Binary Tree

Link to original Problem on LeetCode

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Note: A leaf is a node with no children.

Example:

Given binary tree [3,9,20,null,null,15,7],

return its depth = 3.

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Solution (Iterative using breadth first search):

class Solution(object):
    def maxDepth(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        # Do BFS and at each level increase the count
        if root is None:
            return 0
        
        queue, count = [root], 0
        
        while queue:
            count += 1
            for i in range(len(queue)):
                node = queue.pop(0)
                if node.left:
                    queue.append(node.left)
                if node.right:
                    queue.append(node.right)
            print
        return count

Solution (Recursive using depth first search):

class Solution(object):
    def maxDepth(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        # Using DFS keep the max count in each recursive call
        if root == None:
            return 0
        
        return 1 + max(self.maxDepth(root.left), self.maxDepth(root.right))