codility solution permutation check javascript solution 100%

Perm Check Codility 100% Correct Javascript Solution

The Perm Check Challenge defines a permutation as a sequence containing each element from 1 to N once, and only once. So the order does not matter.

I devised an algorithm which solves the problem with O(N) or O(N * log(N)) complexity.

I look first for the maximum value of the array, N. Then, if the length of the array is different than N, I return 0 – this is not a permutation.

Moving on, then I counted the occurrences of each element in the array in a new array, B. If there is no value 0 in the array, then A was a permutation, otherwise, it was not.

Here is the code:

function solution(A) {
    // write your code in JavaScript (Node.js 8.9.4)
    let max = 0
    for (let i = 0; i < A.length; i++){
        if (A[i] > max) max = A[i]

    if (A.length !== max) return 0
    let Indexes = Array(max).fill(0)
    for (let i = 0; i < A.length; i++){
    result = Indexes.indexOf(0)
    if (result === -1) {
        return 1
    } else {
        return 0

And here is the report.
Tell me in the comments if you used a more optimized version!

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