class Solution:
    def pathSum(self, root: Optional[TreeNode], targetSum: int) -> List[List[int]]:
        result = []
        
        def dfs(node, remaining_sum, current_path):
            if not node:
                return
            
            # 1. Add current node to path and update sum
            current_path.append(node.val)
            
            # 2. Check if it's a leaf node and sum matches
            if not node.left and not node.right and remaining_sum == node.val:
                # Important: Append a copy ([:]) of the list, 
                # otherwise backtracks will affect the result.
                result.append(current_path[:])
            
            # 3. Traverse children
            else:
                dfs(node.left, remaining_sum - node.val, current_path)
                dfs(node.right, remaining_sum - node.val, current_path)
            
            # 4. Backtrack: Remove current node to prepare for the next branch
            current_path.pop()
            
        dfs(root, targetSum, [])
        return result