1110-delete-nodes-and-return-forest.adoc

1110. Delete Nodes And Return Forest

{leetcode}/problems/delete-nodes-and-return-forest/[LeetCode - 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]]

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.

思路分析

利用递归，在“后序遍历”阶段，对当前阶段判断是否需要删除。

link:{sourcedir}/_1110_DeleteNodesAndReturnForest.java[role=include]

参考资料

1. 1110. 删点成林 - 官方题解

2. 1110. 删点成林 - 简洁写法！