摘要

本博文主要介绍平衡二叉树问题包括，二叉树的高度差，是否为平衡二叉树，有序链表转二叉搜索树，将二叉搜索树变平衡等。

一、平衡二叉树详解

1.1 判断二叉树是否平衡

/*** 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 {public boolean isBalanced(TreeNode root) {if (root == null) {return true;}return getHeight(root) == -1 ? false : true;}public int getHeight(TreeNode root) {if (root == null) {return 0;}int leftH = getHeight(root.left);if (leftH == -1) {return -1;}int rightH = getHeight(root.right);if (rightH == -1) {return -1;}return Math.abs(leftH - rightH) > 1 ? -1 : 1 + Math.max(leftH, rightH);}
}

二·、平衡二叉树相关问题

110. 平衡二叉树

109. 有序链表转换二叉搜索树

1382. 将二叉搜索树变平衡

博文参考

《leetcode》