Union of Sorted Arrays

Problem

Merge two sorted arrays into their sorted union without duplicates.

Advance two pointers, always taking the smaller current value, and skip a value when it equals the last one appended. Both inputs are sorted in non-decreasing order.

Return the union as a sorted list of unique values.

Hint

Skip a value whenever it matches the last element already in the output.

Test cases

case 1

in: [[1,2,3],[2,3,4]]

expected: [1,2,3,4]

case 2

in: [[],[]]

expected: []

case 3

in: [[1,1,2],[2,3]]

expected: [1,2,3]

case 4

in: [[-3,0],[0,5]]

expected: [-3,0,5]

Starter codePython

def union_sorted(a, b):
    # Your code here
    pass

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