814. Binary Tree Pruning
题目描述
We are given the head node root of a binary tree, where additionally every node’s value is either a 0 or a 1.
Return the same tree where every subtree (of the given tree) not containing a 1 has been removed.
(Recall that the subtree of a node X is X, plus every node that is a descendant of X.)
Example 1:
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Example 2:
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Example 3:
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Note:
The binary tree will have at most 100 nodes.
The value of each node will only be 0 or 1.
题目大意
给定以二叉树,每个节点值为 0 或者 1。
删除每个不包含 1 的子树。
解题思路
遍历二叉树,如果根节点值为 1 或者 左子树不为空 或者 右子树不为空,返回 根节点,否则返回nil。
代码
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