Count Subarrays with XOR K

Problem

Count the contiguous subarrays whose XOR equals k.

Maintain counts of prefix XOR values; for each new prefix p, the number of earlier prefixes equal to p XOR k gives the subarrays ending here. Runs in O(n) time.

Hint

XOR is its own inverse, so the needed earlier prefix is prefix XOR k.

Test cases

case 1

in: [[4,2,2,6,4],6]

expected: 4

case 2

in: [[1,1,1],0]

expected: 2

case 3

in: [[1],1]

expected: 1

case 4

in: [[],0]

expected: 0

case 5

in: [[0],0]

expected: 1

Starter codePython

def subarrays_xor_k(nums, k):
    # Your code here
    pass

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