Snapshot Array

Understand how to implement a Snapshot Array in JavaScript by creating custom data structures. Learn to manage indexed values, save snapshots, and retrieve historical data by snapshot ID.

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Statement

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

Constructor (length): This is the constructor and it 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 $1$ , as we start the count at $0$ . The first time this function is called, it saves a snapshot and returns $0$ . The $n^{th}$ time it is called, after saving the snapshot, it returns $n-1$ .
Get Value (idx, Snap ID) method returns the value at the index in the snapshot with the given Snap ID.

Suppose that we have three nodes whose values we wish to track in the snapshot array. Initially, the value of all the nodes will be $0$ . After calling the Set Value (1, 4) function, the value of node 1 will change to $4$ . If we take a snapshot at this point, the current values of all the nodes will be saved with Snap ID $0$ . Now, if we call Set Value (1, 7), the current value for node 1 will change to $7$ . Now, if we call the Get Value (1, 0) function, we will get the value of node 1 from snapshot $0$ , that is, $4$ .

Constraints:

$1 \leq$ length $\leq 1000$
$0 \leq$ idx $<$ length
$0 \leq$ val $\leq 10^9$
$0 \leq$ snapid $<$ (the total number of times we call Snapshot)
At most $5 \times 10^3$ calls will be made to Set Value, Snapshot, and Get Value.

Snapshot Array

Select the correct output for the given code:

snapshot array = Constructor(3)
snapshot array.set value(0, 4)
snapshot array.snapshot()
snapshot array.get value(0, 0)
snapshot array.set value(1, 6) 
snapshot array.snapshot()
snapshot array.get value(1, 1)

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JavaScript

usercode > snapshot_array.js

class SnapshotArray {
    // Constructor
    constructor(length) {
        // Write your code here
    }
    // Function setValue sets the value at a given index idx to val.
    setValue(idx, val) {
        // Write your code here
    }
    // This function takes no parameters and returns the snapID.
    // snapID is the number of times that the snapshot() function was called minus 1.
    snapshot() {
        // Replace this placeholder return statement with your code
        return -1
    }
    // Function getValue returns the value at the index idx with the given snapID.
    getValue(idx, snapID) {
        // Replace this placeholder return statement with your code
        return -1
    }
}
export default SnapshotArray;

Snapshot Array

Snapshot Array

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