Balanced Binary Tree

 

 

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