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Top Apple Coding Interview Questions

Problem title

Difficulty

Avg time to solve

Largest Tree Value

Moderate

25 mins

Sum of Distance

Hard

25 mins

Factor Combinations

Moderate

35 mins

Count the repetitions

Hard

25 mins

Longest Duplicate SubString

Moderate

30 mins

Construct Binary Tree From Inorder and Preorder Traversal

Easy

10 mins

Vertical Order Traversal

Moderate

35 mins

Serialize/Deserialize The Binary Tree

Hard

15 mins

Tic-Tac-Toe Winner

Easy

20 mins

Find the Good Matrix

Moderate

30 mins

Problem

Submissions

7

Avg. time to solve

15 min

Success Rate

85%

Problem Statement

```
Serialization is the process of translating a data structure or object state into a format that can be stored or transmitted (for example, across a computer network) and reconstructed later. The opposite operation that is, extracting a data structure from stored information, is deserialization.
```

```
The first line contains an integer 'T' which denotes the number of test cases or queries to be run. Then the test cases follow.
The only line of each test case contains elements in the level order form. The line consists of values of nodes separated by a single space. In case a node is null, we take -1 in its place. So -1 would not be a part of the tree nodes.
```

```
The input for the tree depicted in the below image will be:
```

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

```
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).
```

```
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
```

```
For each test case, print the level order traversal of the deserialized binary tree separated by single spaces, for NULL nodes print -1.
Print the output of each test case in a separate line.
```

```
You don’t need to print anything; It has already been taken care of.
```

```
1 <= T <= 100
0 <= N <= 5000
1 <= data <= 10^5 and data != -1
Time Limit: 1 sec
```

```
2
1 -1 3 -1 -1
3 4 -1 -1 -1
```

```
1 -1 3 -1 -1
3 4 -1 -1 -1
```

```
For the first test case, the level order traversal of the given tree will be “1 -1 3 -1 -1” where -1 denotes the null nodes.
For the second test case, the level order traversal of the given tree will be “3 4 -1 -1 -1” where -1 denotes the null nodes.
```

```
2
1 2 3 -1 4 5 -1 -1 -1 -1 -1
2 1 3 4 -1 -1 5 -1 -1 -1 -1
```

```
1 2 3 -1 4 5 -1 -1 -1 -1 -1
2 1 3 4 -1 -1 5 -1 -1 -1 -1
```

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