Sales by Match (Hackerank) solved using Kotlin


There is a large pile of socks that must be paired by color. Given an array of integers representing the color of each sock, determine how many pairs of socks with matching colors there are.


There is one pair of color and one of color . There are three odd socks left, one of each color. The number of pairs is.

Function Description

Complete the sockMerchant function in the editor below.

sockMerchant has the following parameter(s):

  • int n: the number of socks in the pile


  • int: the number of pairs

Input Format

The first line contains an integer, the number of socks represented in.
The second line contains space-separated integers, the colors of the socks in the pile.

Sample Input

STDIN                       Function
----- --------
9 n = 9
10 20 20 10 10 30 50 10 20 ar = [10, 20, 20, 10, 10, 30, 50, 10, 20]

Sample Output



There are three pairs of socks.


From the explanation, we need to get the pairs of duplicated values in the array.

Note: if the pair is 3 it will be counted as 1

Sample array

val ty = arrayOf(10, 20, 20, 10, 10, 30, 50, 10, 20)

First Step: is to get the list of duplicated value and their count.

you will use “groupBy” to get the group of each element

val mapva = ty.groupBy { it }

Result: {10=[10, 10, 10, 10], 20=[20, 20, 20], 30=[30], 50=[50]}

Then you use the “mapValues” to create a “Map”get the count of each value as key and value

val mapval = ty.groupBy { it } .mapValues { it.value.count() }

Result: {10=4, 20=3, 30=1, 50=1}

Second Step: Create a variable that will hold the count of duplicated value

var sock_count = 0for (u in mapval) {

if (u.value >= 2) {
sock_count += u.value / 2


loop through the values in the Map, check if any value is greater than or equal to 2 if yes divide them by 2, and add them to the “sock_count” variable.

Third Step: Print the “sock_count”.

Cheers 🥳🥳🥳🥳🥳🥳🥳

Thanks for reading.

A software engineer with considerable experience in mobile development, native Android, and IOS development(Xcode), flutter dev, technical writing and community

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store