110.Balanced Binary Tree

https://leetcode.com/problems/balanced-binary-tree/

1.Description(Easy)

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

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.

2.Code

 public boolean isBalanced(TreeNode root){
     if(root==null){
         return true;
     }
     if(root.left==null && root.right==null){
         return true;
     }
     int diff=Math.abs(getHeight(root.left)-getHeight(root.right));
     if(diff>1){
         return false;
     }
     else{
         return isBalanced(root.left)&&isBalanced(root.right);
     }
 }

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