题目 You need to find the largest value in each row of a binary tree. Example: {代码...} 讲解 又是树的层次遍历题。相同的题我已经做了两个了：637. Average of Levels in Binary Tree、429. N-ary Tree Level Order Traversal Java代码 {代码...}

Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.

Given an n-ary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might need to change the root of the tree, so the result should return the new root of the trimmed binary search tree.

Given a tree, rearrange the tree in in-order so that the leftmost node in the tree is now the root of the tree, and every node has no left child and only 1 right child.

Consider all the leaves of a binary tree. From left to right order, the values of those leaves form a leaf value sequence.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Given an n-ary tree, return the postorder traversal of its nodes' values.

Given an n-ary tree, return the preorder traversal of its nodes' values.