Find the stray number

Find the stray numberCodewars

Approach

1. find unique number though Set() and assign value to 'a' and 'b'

2. if inputs first indexOf 'a' and inputs lastIndexOf 'a' is same 'a' is unique, return 'a' otherwise return 'b'

Solution

JavaScript

const stray = (numbers) => {
  const [a, b] = [...new Set(numbers)];
  return numbers.indexOf(a) === numbers.lastIndexOf(a) ? a : b;
};