Package g1101_1200.s1146_snapshot_array

Class SnapshotArray

java.lang.Object
g1101_1200.s1146_snapshot_array.SnapshotArray
public class SnapshotArray extends java.lang.Object
1146 - Snapshot Array.

Medium

Implement a SnapshotArray that supports the following interface:

  • SnapshotArray(int length) initializes an array-like data structure with the given length. Initially, each element equals 0.
  • void set(index, val) sets the element at the given index to be equal to val.
  • int snap() takes a snapshot of the array and returns the snap_id: the total number of times we called snap() minus 1.
  • int get(index, snap_id) returns the value at the given index, at the time we took the snapshot with the given snap_id

Example 1:

Input: [“SnapshotArray”,“set”,“snap”,“set”,“get”] [[3],[0,5],[],[0,6],[0,0]]

Output: [null,null,0,null,5]

Explanation:

SnapshotArray snapshotArr = new SnapshotArray(3); // set the length to be 3 snapshotArr.set(0,5); // Set array[0] = 5 snapshotArr.snap(); // Take a snapshot, return snap_id = 0 snapshotArr.set(0,6); snapshotArr.get(0,0); // Get the value of array[0] with snap_id = 0, return 5

Constraints:

  • 1 <= length <= 50000
  • At most 50000 calls will be made to set, snap, and get.
  • 0 <= index < length
  • 0 <= snap_id <(the total number of times we call snap())
  • 0 <= val <= 10^9

  • Constructor Summary

    Constructors
    Constructor
    Description
    SnapshotArray(int length)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    get(int index, int snapId)
     
    void
    set(int index, int val)
     
    int
    snap()
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • SnapshotArray

      public SnapshotArray(int length)

  • Method Details

    • set

      public void set(int index, int val)

    • snap

      public int snap()

    • get

      public int get(int index, int snapId)