Mismatch Array

Problem

Given an array nums containing n numbers taken from the range 1 to n, it is known that one number from the set {1, 2, ..., n} is missing and one number appears twice in nums.

Return these two numbers in the form of an array.

Examples

findErrorNums([5, 3, 2, 7, 6, 6, 1, 4])
// returns [6, 8]
// The number 6 is duplicated and the item 8 is missing.

findErrorNums([2, 3, 3, 4, 5, 6, 7, 8, 9, 10])
// returns [3, 1]
// The number represented by 3 appears twice
// while the item 1 is absent.