Balance Tree Check

isBalanceTree

public class Solution {
    public boolean isBalanced(TreeNode root) {
        if(root == null) return true; 
        if(checkHeight(root) == -1) return false;
        else return true;
    }
    
    int checkHeight(TreeNode node) {
        if(node == null) return 0;
        int leftHeight = checkHeight(node.left);
        if(leftHeight == -1) return -1;
        int rightHeight = checkHeight(node.right);
        if(rightHeight == -1) return -1;
        if(Math.abs(leftHeight - rightHeight) > 1) return -1;
        else return Math.max(leftHeight, rightHeight) + 1;
    }
}