leetcode_question_113 Path Sum II

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:
Given the below binary tree and  sum = 22 ,

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

return

[
   [5,4,11,2],
   [5,8,4,5]
]

DFS:

void findPathSum(TreeNode* root, vector<int> &path, vector<vector<int>> &allpath, int sum)
    {
    	path.push_back(root->val);
		if(root->left == NULL && root->right == NULL){
			vector<int>::iterator it = path.begin();
			int tmpsum = 0;
			for(; it != path.end(); ++it)
				tmpsum += *it;
			if(tmpsum == sum){
				allpath.push_back(path);}
			path.pop_back();
			return;
		}

		if(root->left)
			findPathSum(root->left,path,allpath,sum);
		if(root->right)
			findPathSum(root->right,path,allpath,sum);
		path.pop_back();
	}
	vector<vector<int> > pathSum(TreeNode *root, int sum) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<vector<int>> allpath;
		if(root == NULL)
			return allpath;
		vector<int> path;
		findPathSum(root, path, allpath, sum);
		return allpath;
    }