How can i sort a medal table array in Kotlin?

June 10, 2022

I’m working for a school project and i need to sort a multidimensional array using Kotlin. The array contains arrays of medals. I need to sort it like a medal table, where depending on the medal weight and medals count.

The array is something like this:

[0] -> [0,0,0,0,0] (for each index there is an array of 5 medals, each medal has a weight from 0 to 4, 0 is the is the least important, 4 is the most.

Example of populated array:

[0] -> [0,17,0,0,2]
[1] -> [1,0,0,0,0]
[2] -> [0,12,39,21,0]
[3] -> [0,13,0,11,17]

I need something like this:

[1] -> [1,0,0,0,0]
[0] -> [0,17,0,0,2]
[3] -> [0,13,0,11,17]
[2] -> [0,12,39,21,0]

Thank you very much.

>Solution :

You can use sortedArrayWith that takes a Comparator

Multiple options.

val medals = arrayOf(
    arrayOf(0,17,0,0,2), 
    arrayOf(1,0,0,0,0), 
    arrayOf(0,12,39,21,0), 
    arrayOf(0,13,0,11,17)
)

val sorted = medals.sortedArrayWith { a1, a2 ->
    a1.zip(a2)
        .find { it.first != it.second }
        ?.let { it.second - it.first } ?: 0
}

val sorted = medals.sortedArrayWith { a1, a2 ->
   a1.zip(a2).forEach {
        if(it.first != it.second) return@sortedArrayWith it.second-it.first
    }
    0
}

Idea is to find the first pair/index where the counts don’t match, and return the maximum value.

The solution is generic that would work with any size of nested array