leetcode Question 48: Maximum Depth of Binary Tree

Maximum Depth of Binary Tree

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.

Analysis:

This is an easy problem.
Either DFS (depth first search) or BFS(breadth first search).
Details see source code.
C++:     DFS
Python: BFS

Code(C++):

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (!root){return 0;}
        else{
            return max(maxDepth(root->right)+1,maxDepth(root->left)+1);
        }
    }
};

Code(Python):

# Definition for a  binary tree node
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    # @param root, a tree node
    # @return an integer
    def maxDepth(self, root):
        if root == None:
            return 0
        q = []
        q.append([root, 1])
        res = 0
        while len(q) != 0:
            node, dep = q.pop()
            res = max(res, dep)
            if node.left != None:
                q.append([node.left, dep + 1])
            if node.right != None:
                q.append([node.right, dep + 1])
        return res