Package g1101_1200.s1146_snapshot_array

Class SnapshotArray

java.lang.Object
g1101_1200.s1146_snapshot_array.SnapshotArray
public class SnapshotArray extends 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 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)