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'''
Author : MiKueen
Level : Medium
Problem Statement : Path Sum II
Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.
Note: A leaf is a node with no children.
Example:
Given the below binary tree and sum = 22,
5
/ \
4 8
/ / \
11 13 4
/ \ / \
7 2 5 1
Return:
[
[5,4,11,2],
[5,8,4,5]
]
'''
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def pathSum(self, root, sum):
"""
:type root: TreeNode
:type sum: int
:rtype: List[List[int]]
"""
# DFS solution
if not root:
return []
if root.left is None and root.right is None:
if sum == root.val:
return [[root.val]]
else:
return []
res = []
left, right = [], []
sum -= root.val
if root.left:
left = self.pathSum(root.left, sum)
if root.right:
right = self.pathSum(root.right, sum)
for l in left:
res.append([root.val] + l)
for r in right:
res.append([root.val] + r)
return res