Swift compare 2 array of type [int] without guaranteed order

Question

I make app for performing tests. For check for valid answer i have array of correct answers, of type [Int]. It may be, for example, [1, 5, 10].

Also i have array of questions id's that user entered, also [Int] type.

Now i have to somehow compare that arrays. But, [1,5,10] should be equal to [10,1,5] and [5,1,10], etc., because order is not guaranteed. How to achieve that?

And if your need to deal with duplicate values in the array then https://stackoverflow.com/questions/40883818/check-if-elements-in-two-arrays-are-same-irrespective-of-index is a better duplicate. — rmaddy, Aug 29 '17 at 15:45

score 1 · Accepted Answer · answered Aug 29 '17 at 15:37

1

If you want a function that returns true if an array contains all elements of your array and only those elements, you can use below Array Extension. If the length of the two arrays isn't the same or if one of the elements in your array isn't present in the other array, the function returns false, otherwise it returns true.

let array1 = [1,5,10]
let array2 = [5,10,1]
let array3 = [10,1,5]
let otherArray = [2,1,5,10]
let anotherArray = [2,3,5]

extension Array where Element == Int {
    func isUnorderedEqual(to array: [Element])->Bool{
        if self.count == array.count {
            for element in self {
                if array.index(of: element) == nil {
                    return false
                }
            }
            return true
        } else {
            return false
        }
    }
}

print(array1.isUnorderedEqual(to: array2)) //true
print(array1.isUnorderedEqual(to: array3)) //true
print(array1.isUnorderedEqual(to: otherArray)) //false
print(array1.isUnorderedEqual(to: anotherArray)) //false

answered Aug 29 '17 at 15:37

Dávid Pásztor

51,403
9
85
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what happens when there are duplicates? – Aug 29 '17 at 15:42
If the duplicates exist in both arrays, it returns true, otherwise false. Since the question didn't specify the case of duplicates, I didn't specify it either. – Dávid Pásztor Aug 29 '17 at 15:43
duplicate Question :) – Abdelahad Darwish Aug 29 '17 at 15:47
1

This is really suboptimal... `O(N^2)`. A set-based solution can do this is in `O(4*n)` – Alexander Aug 29 '17 at 16:11
1

Since OP didn't specify what to do with duplicate elements, I didn't want to use `Set`, which would discard all duplicates automatically, but you are right, an `NSCountedSet` based solution could be used. – Dávid Pásztor Aug 29 '17 at 16:17

score -1 · Answer 2 · answered Aug 29 '17 at 15:40

-1

You can filter for any correct answers not in the list of answers and look if any such item exists.

let correctAnswers: [Int] = [1, 5, 10]

func validate(answers: [Int]) -> Bool {
    return answers.filter({ answer in !correctAnswers.contains(answer) }).isEmpty
}

validate(answers: [10, 1, 5])

answered Aug 29 '17 at 15:40

Francis.Beauchamp

1,323
15
28

1

what happens when there are duplicates? – Aug 29 '17 at 15:42
Given two lists of the same size such as OP uses, then when there are duplicates, `answers` will obviously have items not in the `correctAnswers` list ... – Francis.Beauchamp Aug 29 '17 at 15:43

Swift compare 2 array of type [int] without guaranteed order

2 Answers2