Path Sum II

Given the root of a binary tree and an integer targetSum, return all root-to-leaf paths where the sum of the node values in the path equals targetSum. Each path should be returned as a list of the node values, not node references.

A root-to-leaf path is a path starting from the root and ending at any leaf node. A leaf is a node with no children.

Example 1:

Input: root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
Output: [[5,4,11,2],[5,8,4,5]]
Explanation: There are two paths whose sum equals targetSum:
5 + 4 + 11 + 2 = 22
5 + 8 + 4 + 5 = 22

Example 2:

Input: root = [1,2,3], targetSum = 5
Output: []

Example 3:

Input: root = [1,2], targetSum = 0
Output: []

Solution

class Solution:
    def pathSum(self, root: Optional[TreeNode], targetSum: int) -> List[List[int]]:
        paths = []
        def traverse(node, curr_path, curr_sum):
            if not node:
                return None
            if curr_sum + node.val == targetSum and not node.left and not node.right:
                paths.append(curr_path + [node.val])
            if node.left:
                traverse(node.left, curr_path + [node.val], curr_sum + node.val)
            if node.right:
                traverse(node.right, curr_path + [node.val], curr_sum + node.val)
        traverse(root, [], 0)
        return paths

Table of Contents

Path Sum II

Solution