Path Sum

/**

 * Definition for a binary tree node.

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class Solution {

public:

    bool hasPathSum(TreeNode* root, int sum) {

        if(root==NULL) return false;

        if(root->left ==NULL && root->right == NULL) return root->val==sum;

        if(hasPathSum(root->left,sum-root->val))return true;

        if(hasPathSum(root->right,sum-root->val))return true;

        return false;

    }

};