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(难度Easy) Problem 110. Balanced Binary Tree(判断二叉树是否平衡)

Balanced Binary Tree

Difficulty

Easy

Description

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as:

a binary tree in which the depth of the two subtrees of _every_ node never
differ by more than 1.

Example 1:

Given the following tree [3,9,20,null,null,15,7]:

    3
   / \
  9  20
    /  \
   15   7

Return true.

Example 2:

Given the following tree [1,2,2,3,3,null,null,4,4]:

       1
      / \
     2   2
    / \
   3   3
  / \
 4   4

Return false.

题意

给定一个二叉树,判断二叉树是否是平衡的。二叉树平衡的意思是指树的左右子树的深度差小于等于1.在二叉树当中所谓的深度指的是叶子节点到树根的长度。

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