Distinct.md

Write a function

function solution(A);

that, given a zero-indexed array A consisting of N integers, returns the number of distinct values in array A.

Assume that:

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]. 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.

Complexity:

expected worst-case time complexity is O(N*log(N)); expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments). Elements of input arrays can be modified.

function solution(A) {
    // write your code in JavaScript (Node.js 6.4.0)
    var map = {}
    for (var i in A) {
        if (!map[A[i]]) {
            map[A[i]] = true
        }
    }
    return Object.keys(map).length
}