Find the Added Element | Dataford Interview Questions

Tinder Discovery compares candidate profile identifiers from two processing stages. Given two integer lists that contain exactly the same elements with the same multiplicities, except that one list contains one additional element, return the value of that extra element.

The lists may be in different orders, and values may be repeated. Do not modify either input list.

Formal Specification

Implement find_extra_element(shorter, longer), where shorter and longer are lists of integers and len(longer) == len(shorter) + 1. Return the integer whose occurrence count in longer is one greater than its count in shorter.

Constraints

0 <= len(shorter) <= 100,000
len(longer) == len(shorter) + 1
-10^9 <= value <= 10^9
The lists contain the same multiset except for one extra occurrence in longer

Function Signature

def find_extra_element(shorter, longer):

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Problem