Correct a Binary Tree
给一个二叉树, 其中有一个node是invalid, 这种invalid是他的右子树连到了右边的任意node. 求删除这个错误的子树后的树.
这个题主要是读懂题, 理解这种invalid只能发生在某个node的右子树上. 然后查重要用set. 就没了
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
Set<TreeNode> set = new HashSet<>();
public TreeNode correctBinaryTree(TreeNode root) {
if(root == null)
return root;
if(root.right != null) {
if(root.right.right != null && set.contains(root.right.right)) {
root.right = null;
return root;
}
else{
set.add(root.right);
correctBinaryTree(root.right);
}
}
if(root.left != null) {
if(root.left.right != null && set.contains(root.left.right)) {
root.left = null;
return root;
}
else{
set.add(root.left);
correctBinaryTree(root.left);
}
}
return root;
}
}