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Grokking the Coding Interview Patterns in Go

Solution: Snapshot Array

Explore how to implement a Snapshot Array that supports setting values, taking snapshots, and retrieving past states efficiently. Learn to optimize using nested dictionaries to minimize complexity and handle multiple snapshots with constant time operations for setting and getting values.

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Statement

In this challenge, you have to implement a Snapshot Array with the following properties:

  • NewSnapshotArray (length): Initializes the data structure to hold the specified number of indexes.

  • Set Value (idx, val): This property sets the value at a given index idx to value val.

  • Snapshot(): This method takes no parameters and returns the Snap ID. Snap ID is the number of times that the snapshot function was called, less 11, as we start the count at 00. The first time this function is called, it saves a snapshot and returns 00. The nthn^{th} time it is called, after saving the snapshot, it returns n−1n-1.

  • Get Value (idx, Snap ID) method returns the value at the index in the snapshot with the given Snap ID. ...