0113.cpp

class Solution {
  public:
    vector<vector<int>> pathSum(TreeNode *root, int targetSum) {
        if (!root) return {};
        stack<pair<TreeNode *, int>> st;
        vector<vector<int>> res;
        vector<int> path;
        st.push({root, 0});
        while (!st.empty()) {
            auto [root, sum] = st.top();
            if (sum == INT_MIN) {
                st.pop();
                path.pop_back();
                continue;
            }
            sum += root->val;
            st.top().second = INT_MIN;
            path.push_back(root->val);

            if (!root->left && !root->right && sum == targetSum) res.push_back(path);
            if (root->left) st.push({root->left, sum});
            if (root->right) st.push({root->right, sum});
        }
        return res;
    }
};