README.md

1110. Delete Nodes And Return Forest

Given the root of a binary tree, each node in the tree has a distinct value.

After deleting all nodes with a value in to_delete, we are left with a forest (a disjoint union of trees).

Return the roots of the trees in the remaining forest. You may return the result in any order.

Example 1:

Input: root = [1,2,3,4,5,6,7], to_delete = [3,5] Output: [[1,2,null,4],[6],[7]] 

Example 2:

Input: root = [1,2,4,null,3], to_delete = [3] Output: [[1,2,4]] 

Constraints:

• The number of nodes in the given tree is at most 1000.
• Each node has a distinct value between 1 and 1000.
• to_delete.length <= 1000
• to_delete contains distinct values between 1 and 1000.

Solutions (Python)

1. Solution

# Definition for a binary tree node.# class TreeNode:# def __init__(self, val=0, left=None, right=None):# self.val = val# self.left = left# self.right = rightclassSolution: defdelNodes(self, root: TreeNode, to_delete: List[int]) ->List[TreeNode]: ifrootisNone: return [] ret= [root] left_ret=self.delNodes(root.left, to_delete) right_ret=self.delNodes(root.right, to_delete) ifroot.valinto_delete: returnleft_ret+right_retifroot.leftisnotNone: ifroot.left.valinto_delete: root.left=Noneret+=left_retelse: ret+=left_ret[1:] ifroot.rightisnotNone: ifroot.right.valinto_delete: root.right=Noneret+=right_retelse: ret+=right_ret[1:] returnret

Solutions (Ruby)

1. Solution

# Definition for a binary tree node.# class TreeNode# attr_accessor :val, :left, :right# def initialize(val = 0, left = nil, right = nil)# @val = val# @left = left# @right = right# end# end# @param {TreeNode} root# @param {Integer[]} to_delete# @return {TreeNode[]}defdel_nodes(root,to_delete)return[]ifroot.nil?ret=[root]left_ret=del_nodes(root.left,to_delete)right_ret=del_nodes(root.right,to_delete)returnleft_ret + right_retifto_delete.include?(root.val)unlessroot.left.nil?ifto_delete.include?(root.left.val)root.left=nilret += left_retelseret += left_ret[1..]endendunlessroot.right.nil?ifto_delete.include?(root.right.val)root.right=nilret += right_retelseret += right_ret[1..]endendretend