Paths from root with a specified sum | C++, Java,

Can someone explain whats wrong with my brute force pls 😀
class Solution_ {

public:

void helper(Node *root, int currSum, int targetSum, vector<int> &curr,

vector<vector<int>> &res) {

if (currSum == targetSum) res.push_back(curr);

if (root == nullptr) return;

curr.push_back(root->key);

helper(root->left, currSum + root->key, targetSum, curr, res);

helper(root->right, currSum + root->key, targetSum, curr, res);

curr.pop_back();

}

vector<vector<int>> printPaths(Node *root, int sum) {

vector<vector<int>> res;

vector<int> curr;

helper(root, 0, sum, curr, res);

return res;

}

};