110. Balanced Binary Tree

#### QUESTION:

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.

#### SOLUTION:

``````public class Solution {
public boolean isBalanced(TreeNode root) {
if(root == null) return true;
int left = treeHeight(root.left);
int right = treeHeight(root.right);
if(Math.abs(left-right)>1)
return false;
return isBalanced(root.left)&&isBalanced(root.right);
}
public int treeHeight(TreeNode root){
if(root == null)
return 0;
int left = treeHeight(root.left);
int right = treeHeight(root.right);
return left>right?left+1:right+1;
}
}

public class Solution {
public boolean isBalanced(TreeNode root) {
return treeHeight(root) != -1;
}
public int treeHeight(TreeNode root){
if(root == null)return 0;
int left = treeHeight(root.left);
if(left ==-1) return -1;
int right = treeHeight(root.right);
if(right == -1) return -1;
if(Math.abs(left-right)>1) return -1;
return Math.max(left,right)+1;
}
}
``````
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