Contents.swift

import Foundation

public func solution(_ A : inout [Int]) -> Int {
    // write your code in Swift 4.2.1 (Linux)
    
    if A.count == 0 {
        return 0
    }
    
    let uniqueValues = Set(A)
    return uniqueValues.count
    
}

var A = [2,1,1,2,3,1] // -> 3
var A2 = [-1000000, 1000000]
print(solution(&A2))

// MARK: - Prompt

/*
 Write a function

 public func solution(_ A : inout [Int]) -> Int

 that, given an array A consisting of N integers, returns the number of distinct values in array A.

 For example, given array A consisting of six elements such that:

  A[0] = 2    A[1] = 1    A[2] = 1
  A[3] = 2    A[4] = 3    A[5] = 1
 the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.

 Write an efficient algorithm for the following assumptions:

 N is an integer within the range [0..100,000];
 each element of array A is an integer within the range [−1,000,000..1,000,000].
*/