Read-Your-Writes Queue

Problem

Simulate read-your-writes consistency for a session.

operations contains "write" (keys[i] = values[i], buffered), "flush" (publish buffered writes to the store), or "read" (record the buffered value for keys[i] if present, else the stored value or None).

Return the list of recorded results (None for write and flush).

Hint

A session's buffered writes shadow the committed store until flushed.

Test cases

case 1

in: [["write","read","flush","write","read"],["a","a","","a","a"],[1,0,0,2,0]]

expected: [null,1,null,null,2]

case 2

in: [["read"],["x"],[0]]

expected: [null]

case 3

in: [["write","flush","read"],["k","","k"],[5,0,0]]

expected: [null,null,5]

case 4

in: [["write","write","read","flush","read"],["k","k","k","","k"],[1,2,0,0,0]]

expected: [null,null,2,null,2]

Starter codePython

def ryw_queue(operations, keys, values):
    # Your code here
    pass

4 test cases · run your code against them in the editor