《LeetCode力扣练习》代码随想录——二叉树（平衡二叉树---Java）

《LeetCode力扣练习》代码随想录——二叉树（平衡二叉树—Java）

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刷题思路来源于 代码随想录

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110. 平衡二叉树

• 二叉树-后序遍历

  /**
   * 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 (recursion(root) == -1) {
              return false;
          }
  
          return true;
  
      }
  
      private int recursion(TreeNode root) {
  
          if (root == null) {
              return 0;
          }
  
          int left = recursion(root.left);
          if (left == -1) {
              return -1;
          }
  
          int right = recursion(root.right);
          if (right == -1) {
              return -1;
          }
  
          if ((left > right ? (left - right) : (right - left)) > 1) {
              return -1;
          }
  
          return 1 + (left > right ? left : right);
  
      }
  }
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