Solution: Insert Delete GetRandom O(1)

Learn to implement a custom Random Set data structure that supports insertions, deletions, and random element retrieval all in average constant time. This lesson guides you through optimizing naive approaches by combining arrays and hash maps, understanding the algorithmic trade-offs, and mastering efficient operations needed for coding interviews.

We'll cover the following...

Statement
Solution
- Naive approach
- Optimized approach using an array and a hash map

Statement

Implement a Random Set data structure that can perform the following operations:

Constructor(): This initializes the Random Set object.
Insert(): This function takes an integer, data, as its parameter and, if it does not already exist in the set, add it to the set, returning TRUE. If the integer already exists in the set, the function returns FALSE.
Delete(): This function takes an integer, data, as its parameter and, if it exists in the set, removes it, returning TRUE. If the integer does not exist in the set, the function returns FALSE.
GetRandom(): This function takes no parameters. It returns an integer chosen at random from the set.

Note: Your implementation should aim to have a running time of $O(1)$ (on average) for each operation.

Constraints:

$-2^{31} \leq$ data $\leq 2^{31}$
No more than $2 \times 10^5$

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