Maximum Depth of Binary Tree

​​https://leetcode.com/problems/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.

求给定二叉树的最大的深度，最大深度为最远叶子节点到根节点的距离，即根节点到最远叶子节点的距离.

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
int maxDepth(struct TreeNode* root) {

    if(root ==  NULL)
        return 0;

    int left = maxDepth(root->left);
    int right = maxDepth(root->right);

    return left > right ? left + 1 : right + 1;
}