Good morning! Here's our prompt for today.

Given a binary tree, write a method to return an array containing the largest (by value) node values at each level. In other words, we're looking for the max per level.

So for instance, given the following binary tree, we'd get [2, 7, 9] if the method grabbed the correct maxes.

1/*
2       2
3      / \
4     3   7
5    / \   \  
6   5   8   9 
7*/
8
9maxValPerLevel(root);
10// [2, 7, 9]

Assuming the standard tree node definition of:

1function Node(val) {
2  this.val = val;
3  this.left = this.right = null;
4}

Can you fill it out via the following function signature?

1function maxValPerLevel(root) {
2  // if (!root) { return []; }
3
4  return;
5};

Constraints

• The number of nodes in the given tree <= 100000
• The nodes will always contain integer values between -1000000000 and 1000000000
• Expected time complexity : O(n)
• Expected space complexity : O(n)

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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​

class Node:

    def __init__(self, val):

        self.val = val

        self.left = None

        self.right = None

​

​

def max_per_level(root):

    # fill this in

    return root

​

​

# root = Node(2)

# root.left = Node(3)

# root.right = Node(7)

# root.left.left = Node(5)

# root.left.right = Node(8)

# root.right.right = Node(9)

# print(maxValPerLevel(root))

​

​

# Node definition

class Node:

    def __init__(self, val):

        self.val = val

        self.left = None

        self.right = None

​

​

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