Problem:

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.

 

Solution:

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     struct TreeNode *left; *     struct TreeNode *right; * }; */int maxDepth(struct TreeNode* root) {    int left_depth,right_depth;    if(root == NULL)        return 0;    left_depth = maxDepth(root->left);    right_depth= maxDepth(root->right);    return (left_depth>right_depth)?left_depth+1:right_depth+1;}