Path Sum

    bool hasPathSum(TreeNode *root, int sum) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(root == NULL)
            return false;
        if(sum == root->val && root->left==NULL && root->right==NULL)
            return true;
        return hasPathSum(root->left, sum-root->val)||hasPathSum(root->right, sum-root->val);
    }