package 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.
 *
 * Tags: Tree, DFS
 * Created by Jeffrey on 2016/11/11.
 */
public class BalancedBinaryTree {
    public boolean isBalanced(TreeNode root) {
        return maxDepth(root) != -1;
    }
    public int maxDepth(TreeNode root) {
        if(root == null) return 0;
        int left = maxDepth(root.left);
        int right = maxDepth(root.right);
        if(left == -1 || right == -1 || Math.abs(left - right) > 1)
            return -1;
        return Math.max(left, right) + 1;
    }
}
