Leetcode 110 Balanced Binary Tree

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.

左子树本身平衡＋右子数本身平衡＋左子树与右子数最大深度差小于1

def is_balanced(root)
    return true if not root
    is_balanced(root.left) and is_balanced(root.right) and (max_depth(root.left) - max_depth(root.right)).abs <= 1
end

def max_depth(root)
    root ? [max_depth(root.left),max_depth(root.right)].max + 1 : 0
end