LeetCode: Path Sum

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree and 

sum
= 22

,

5
/ \
4   8
/   / \
11  13  4
/  \      \
7    2      1

return true, as there exist a root-to-leaf path 

5->4->11->2

 which sum is 22.

/**
* 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;

queue<struct TreeNode*> Q;
Q.push(root);

while(!Q.empty()) {
struct TreeNode* tmp = Q.front();
if (tmp->left != NULL) {
tmp->left->val += tmp->val;
Q.push(tmp->left);
}

if (tmp->right != NULL) {
tmp->right->val += tmp->val;
Q.push(tmp->right);
}

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

Q.pop();
}

return false;

}
};