Good morning! Here's our prompt for today.

Can you write a function to see if two binary trees are identical?

1   1         1
2  / \       / \
3 2   3     2   3

The above two trees share the same structure in terms of shape and location of each parent nodes' children.

Additionally, each corresponding nodes at every position has the exact same value. Thus, the above is consideredidentical.

The below two are not identical, because we are missing a child node.

1   1         1
2  / \       / 
3 1   3     3   

The definition of a tree node is as follows:

1function Node(val) {
2  this.val = val;
3  this.left = null;
4  this.right = null;
5}

Constraints

• Number of vertices in both the trees <= 100000
• The trees can also be null
• The values of the vertices in the tree will be 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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    'PASSED: ' + 'assert.deepEqual(identicalTrees(tree3, tree3Clone), true);'

var assert = require('assert');

​

function identicalTrees(tree1, tree2) {

  // fill this in

  return true;

}

​

function Node(val) {

  this.val = val;

  this.left = null;

  this.right = null;

}

​

// Regular binary trees

var tree1 = new Node(4);

tree1.left = new Node(1);

tree1.right = new Node(3);

​

var tree2 = new Node(5);

tree2.left = new Node(10);

tree2.left.left = new Node(17);

tree2.left.right = new Node(3);

tree2.right = new Node(8);

​

// Binary search trees

var tree3 = new Node(6);

tree3.left = new Node(3);

​

var tree4 = new Node(5);

Here's a video of us explaining the solution.

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We'll now take you through what you need to know.

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