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.

/**
 * 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) {
        vector<int> depths;
        int count = 0;
        getDepth(depths, root, count);
        
        int maxDepth = 0;
        for(vector<int>::iterator it = depths.begin(); it != depths.end(); it++)
            if(maxDepth < *it)
                maxDepth = *it;
                
        return maxDepth;
    }
    
    void getDepth(vector<int> &depths, TreeNode *root, int count)
    {
        if(root != NULL)
        {
            count++;
            getDepth(depths,root->left,count);
            getDepth(depths,root->right,count);
        }
        
        depths.push_back(count);
    }
};