5.4.3 Path Sum

Notes:
	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: Recursion.
	*/
	/**
	* Definition for binary tree
	* struct TreeNode {
	* int val;
	* TreeNode *left;
	* TreeNode *right;
	* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
	* };
	*/

<pre name="code" class="cpp">class Solution {
public:
    bool hasPathSum(TreeNode *root, int sum) {
        if (!root)
            return false;
        if (!root->left and !root->right)
            return sum == root->val;
        return hasPathSum(root->left, sum - root->val) || 
               hasPathSum(root->right, sum - root->val);
    }
};