[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.

My Code:

 bool hasPathSum(TreeNode *root, int sum) {

        if(!root) return false;

        queue<TreeNode*> q;

        q.push(root);

        while(!q.empty()){

            TreeNode* cur = q.front();

            if(!cur->left && !cur->right){

                if(cur->val == sum)

                    return true;

            }

            else{

                if(cur->left){

                    cur->left->val = cur->val + cur->left->val;

                    q.push(cur->left);

                }

                if(cur->right){

                    cur->right->val = cur->val + cur->right->val;

                    q.push(cur->right);

                }

            }

            q.pop();

        }

        return false;

    }