# What Is a Skip List Data Structure McQ?

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Angela Bailey

A skip list is a data structure that allows for efficient searching, insertion, and deletion operations. It is similar to a linked list but incorporates a clever design that improves performance by “skipping” over multiple elements at once. In this article, we will explore the skip list data structure and test your knowledge with some multiple-choice questions.

## Introduction to Skip List

A skip list consists of a series of linked lists, each with progressively fewer elements. The top-level list contains all the elements, while subsequent levels contain a fraction of the elements from the previous level. This creates a hierarchical structure that allows for faster search times compared to traditional linked lists.

Question 1: What is the purpose of using multiple levels in a skip list?

• a) To reduce memory usage
• b) To improve search performance
• c) To make the data structure visually appealing
• d) None of the above

Answer: b) To improve search performance.

## Skip List Operations

Skip lists support three primary operations: searching, insertion, and deletion. These operations are performed in a manner similar to linked lists but with additional steps to navigate through different levels.

### Searching in Skip List

To search for an element in a skip list:

1. Start from the top-level head node.
2. If the current node’s value is less than the Target value, move horizontally to the next node on the same level.
3. If the current node’s value is equal to the Target value, return it.
4. If the current node’s value is greater than the Target value, move vertically down to the next level and repeat steps 2-4.
5. If no match is found, return null.

Question 2: What is the time complexity of searching in a skip list?

• a) O(n)
• b) O(log n)
• c) O(1)
• d) O(n log n)

### Insertion in Skip List

To insert an element into a skip list:

1. Perform a search for the Target position where the new element should be inserted.
2. Create a new node with the element’s value.
3. Insert the new node into the appropriate positions across different levels based on a random coin toss. Higher-level insertions are determined by more consecutive “heads” results.

Question 3: What is the average time complexity of insertion in a skip list?

• a) O(n)
• b) O(log n)
• c) O(1)
• d) O(n log n)