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Problem

Submissions

Check Identical Trees

Contributed by

Ashwani

Medium

0/80

Avg time to solve 20 mins

Success Rate 85 %

22 upvotes

Problem Statement

You are given two binary trees with 'N' and 'M' nodes respectively. You need to return true if the two trees are identical. Otherwise, return false.

Below is the example and explanation of Identical trees.

Example :

 For the trees given below:-

The given trees are identical as:-
1. The number of nodes in both trees is the same. 
2. The number of edges in both trees is the same. 
3. The data for root for both the trees is the same i.e 5. 
4. The data of root -> left (root’s left child) for both the trees is the same i.e 2.
5. The data of root -> right (root’s right child) for both the trees is the same i.e 3.
6. The data of root -> right -> left ( left child of root’s right child) for both the trees is the same i.e 6.
7. Nodes with data 2 and 6 are the leaf nodes for both the binary trees.

Detailed explanation ( Input/output format, Notes, Constraints, Images )

Input format :

The first line of input contains an integer T denoting the number of queries or test cases. 

The first line of every test case contains elements in the level order form for the first binary tree. The line consists of values of nodes separated by a single space. In case a node is null, we take -1 on its place.

The second line of every test case contains elements in the level order form for the second tree. The line consists of values of nodes separated by a single space. In case a node is null, we take -1 on its place.

For example, the level order input for the tree depicted in the below image would be :

1
2 3
4 -1 5 6
-1 7 -1 -1 -1 -1
-1 -1

Explanation :

Level 1 :
The root node of the tree is 1

Level 2 :
Left child of 1 = 2
Right child of 1 = 3

Level 3 :
Left child of 2 = 4
Right child of 2 = null (-1)
Left child of 3 = 5
Right child of 3 = 6

Level 4 :
Left child of 4 = null (-1)
Right child of 4 = 7
Left child of 5 = null (-1)
Right child of 5 = null (-1)
Left child of 6 = null (-1)
Right child of 6 = null (-1)

Level 5 :
Left child of 7 = null (-1)
Right child of 7 = null (-1)

The first not-null node (of the previous level) is treated as the parent of the first two nodes of the current level. The second not-null node (of the previous level) is treated as the parent node for the next two nodes of the current level and so on.
The input ends when all nodes at the last level are null (-1).

Note :

The above format was just to provide clarity on how the input is formed for a given tree. 
The sequence will be put together in a single line separated by a single space. Hence, for the above-depicted tree, the input will be given as:

1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Output format :

For each test case, print in a single line either “True” (if the two trees are identical) or “False” otherwise. 

The output of each test case will be printed in a separate line.

Note :

You do not need to print anything, it has already been taken care of. Just implement the given function.

Constraints :

1 <= T <= 10
0 <= N <= 10^5
0 <= M <= 10^5
1 <= Node Data <= 10^9 

Time limit: 1 sec

Sample input 1 :

2
5 2 3 -1 6 -1 -1 -1 -1
5 2 3 -1 6 -1 -1 -1 -1
1 -1 2 -1 -1
1 2 -1 -1 -1

Sample output 1 :

True
False

Explanation for Sample Input 1 :

For test case 1: Refer to the example given above in the problem description.

For test case2: The trees given in the input can be represented as below:-

Although the following conditions satisfy:

The number of nodes in both trees is the same.
The number of edges in both trees is the same. 
The data for root for both the trees is the same i.e 1.

It’s visible from the pictorial representation that the trees are not identical. Reason being:
In Binary tree 1, root’s right is NULL but it’s not true for Binary tree 2. 
In Binary tree 1, root’s left is not NULL but it’s not true for Binary tree 2.

Sample input 2 :

2
4 9 -1 1 2 -1 -1 -1 -1
4 9 -1 1 2 -1 -1 -1 -1
6 2 3 4 5 7 8 -1 -1 -1 -1 -1 -1 -1 -1  
6 2 3 4 5 8 7 -1 -1 -1 -1 -1 -1 -1 -1

Sample output 2 :

True
False

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