#1146

Snapshot Array

expert · 1055 · lc medium +32 · 36.7% accepted · 3,915 likes · top 14%

Description

Build a SnapshotArray data structure that supports these operations:

- SnapshotArray(int length) constructs the structure with the given length, initializing all elements to 0.

- void set(index, val) updates the element at position index to val.

- int snap() captures the current state of the array and returns the snap_id, equal to the number of previous snap() calls.

- int get(index, snap_id) retrieves the value at position index as it was when the snapshot with the given snap_id was taken.

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

Code

class SnapshotArray:

    def __init__(self, length: int):
        

    def set(self, index: int, val: int) -> None:
        

    def snap(self) -> int:
        

    def get(self, index: int, snap_id: int) -> int:
        


# Your SnapshotArray object will be instantiated and called as such:
# obj = SnapshotArray(length)
# obj.set(index,val)
# param_2 = obj.snap()
# param_3 = obj.get(index,snap_id)

class SnapshotArray:

    def __init__(self, length: int):
        

    def set(self, index: int, val: int) -> None:
        

    def snap(self) -> int:
        

    def get(self, index: int, snap_id: int) -> int:
        


# Your SnapshotArray object will be instantiated and called as such:
# obj = SnapshotArray(length)
# obj.set(index,val)
# param_2 = obj.snap()
# param_3 = obj.get(index,snap_id)