113. Path Sum II

Medium

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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:
 []

Constraints:

• The number of nodes in the tree is in the range [0, 5000].

• -1000 <= Node.val <= 1000

• -1000 <= targetSum <= 1000

Solution 1

class Solution:
    def pathSum(self, root: Optional[TreeNode], targetSum: int) -> List[List[int]]:
        self.target = targetSum
        self.result = []
        self.dfs(root, 0 , [])
        return self.result
    
    def dfs(self, node, total = 0, path = []):
        if not node:
            return
        total += node.val
        path.append(node.val)
        if total == self.target and not node.left and not node.right:
            self.result.append(path)
            return
        self.dfs(node.left, total, path[::])
        self.dfs(node.right, total, path[::])

Solution 2

class Solution:
    def pathSum(self, root: Optional[TreeNode], targetSum: int) -> List[List[int]]:
        result=[]
        def recursion(root, current , target, result):
            # print(root.val)
            if not root:
                return
            if not root.left and not root.right and target - (root.val) == 0:
                result.append(current + [root.val])
                return
            recursion(root.left, current + [root.val], target-root.val, result)
            recursion(root.right, current + [root.val], target-root.val, result)
        recursion(root, [] , targetSum, result)
        return resultpy