How to determine if binary tree is balanced?

Question

It\'s been a while from those school years. Got a job as IT specialist at a hospital. Trying to move to do some actual programming now. I\'m working on binary trees now, a

Answer 1

Post order solution, traverse the tree only once. Time complexity is O(n), space is O(1), it's better than top-down solution. I give you a java version implementation.

public static  boolean isBalanced(TreeNode root){
    return checkBalance(root) != -1;
}

private static  int checkBalance(TreeNode node){
    if(node == null) return 0;
    int left = checkBalance(node.getLeft());

    if(left == -1) return -1;

    int right = checkBalance(node.getRight());

    if(right == -1) return -1;

    if(Math.abs(left - right) > 1){
        return -1;
    }else{
        return 1 + Math.max(left, right);
    }
}