Given the tree with root value 1, left child 2, right child 3, and targetSum = 3, what is the final value of result after the loop finishes?

Consider the following iterative DFS code snippet for counting paths with sum equal to targetSum in a binary tree. Given the tree with root value 1, left child 2, right child 3, and targetSum = 3, what is the final value of result after the loop finishes?

class Solution:
    def pathSum(self, root, targetSum):
        if not root:
            return 0
        prefix_counts = {0: 1}
        result = 0
        stack = [(root, 0, False)]  # node, current_sum, visited_children

        while stack:
            node, current_sum, visited = stack.pop()
            if node is None:
                continue
            if not visited:
                current_sum += node.val
                result += prefix_counts.get(current_sum - targetSum, 0)
                prefix_counts[current_sum] = prefix_counts.get(current_sum, 0) + 1
                stack.append((node, current_sum, True))  # Mark node as visited
                stack.append((node.right, current_sum, False))
                stack.append((node.left, current_sum, False))
            else:
                prefix_counts[current_sum] -= 1

        return result