BalancedBinaryTree.md

##Balanced Binary Tree

40% Accepted

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.

Have you met this question in a real interview? Yes
Example
Given binary tree A={3,9,20,#,#,15,7}, B={3,#,20,15,7}

A)  3            B)    3
   / \                  \
  9  20                 20
    /  \                / \
   15   7              15  7
The binary tree A is a height-balanced binary tree, but B is not.

####Tags Expand

• Binary Search
• Divide and Conquer
• Recursion

####思路

####我的代码

/**

• Definition of TreeNode:
• public class TreeNode {

• public int val;
  

• public TreeNode left, right;
  

• public TreeNode(int val) {
  

•     this.val = val;
  

•     this.left = this.right = null;
  

• }
  

• } */

public class Solution { /** * @param root: The root of binary tree. * @return: True if this Binary tree is Balanced, or false. */ public boolean balanced = true;

public boolean isBalanced(TreeNode root) {
    // write your code here
    if (root == null) {
        return true;
    }
    
    getHeight(root);
    
    return balanced;
}

public int getHeight(TreeNode root) {
    if (root == null) {
        return 0;
    }
    
    int left = getHeight(root.left);
    int right = getHeight(root.right);
    if (Math.abs(left - right) > 1) {
        balanced = false;
    }
    
    return Math.max(left, right) + 1;
}

}