[codelab] Given a binary tree, find its maximum depth.

Solution.cpp

/**
 * 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) {
            // Corner case. Should never be hit unless the code is called on root = NULL
            if (root == NULL) return 0;
            // Base case : Leaf node. This accounts for height = 1.
            if (root->left == NULL && root->right == NULL) return 1;

            if (!root->left) return maxDepth(root->right) + 1;
            if (!root->right) return maxDepth(root->left) + 1;

            return max(maxDepth(root->left), maxDepth(root->right)) + 1; 
        }
};

Solution.java

/**
 * Definition for binary tree
 * class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
	public int maxDepth(TreeNode a) {
	    
	    if (a == null) {
	        return 0;
	    }
	    int leftDepth = maxDepth(a.left) + 1;
	    int rightDepth = maxDepth(a.right) + 1;
	    return java.lang.Math.max (leftDepth, rightDepth);
	}
}