Selection Sort Algorithm in Kotlin
Selection sort algorithm was developed using comparison algorithm.
This algorithm picks an element from the left-hand side and finds the smallest element on the right-hand side,
finally it swaps the smallest element to its position and it continues the process for each element with direction left to right except the last element.
But it's not an efficient on medium or large data sets.
Time Complexity
- Best complexity: n^2
- Average complexity: n^2
- Worst complexity: n^2
Selection Sort Implementation in Kotlin
Kotlin Input Screen
fun selectionSort(arr: IntArray) {
val lastIndex: Int = arr.size - 1
for (i in 0..(lastIndex - 1)) {
var minIndex = i
for (j in (i+1)..lastIndex) {
if(arr[minIndex] > arr[j]) {
minIndex = j
}
}
val temp = arr[minIndex]
arr[minIndex] = arr[i]
arr[i] = temp
}
}
fun printArray(arr: IntArray) {
val lastIndex: Int = arr.size - 1;
for (i in 0..lastIndex) {
val num = arr[i]
print("$num ")
}
println("")
}
fun main(args: Array<String>) {
val arr: IntArray = intArrayOf(15, 3, 12, 6, -9, 9, 0);
print("Before Sorting: ")
printArray(arr)
selectionSort(arr)
print("After Sorting: ")
printArray(arr)
}
Kotlin Output Screen
Before Sorting: 15 3 12 6 -9 9 0
After Sorting: -9 0 3 6 9 12 15
Selection sort implementation steps:
Let's take the input array as { 15, 3, 12, 6, -9, 9, 0 } and we can see how the Selection sort is sorting the array.
- Select an index of an element from the left hand-side (i.e. initially an index 0)
- Search an index of the smallest element comparing with all other right-hand side elements with the value of the currently selected index
- Swap the value of the smallest element to the currently selected index
- Apply step 1, 2 and 3, by picking the rest of the element except the last element of an array by incrementing the index value by 1.
Selection Sort Implementation in Kotlin with explanation
Kotlin Input Screen
fun selectionSort(arr: IntArray) {
// Get the last index of an array
val lastIndex: Int = arr.size - 1
// Loop all the element in an array except the last element
for (i in 0..(lastIndex - 1)) {
var minIndex = i
// Find an index of a lowest element in the right-hand side
// corresponding to the element arr[i].
for (j in (i+1)..lastIndex) {
if(arr[minIndex] > arr[j]) {
minIndex = j
}
}
// Swap the lowest element with the current element (i.e. arr[i] <=> arr[minIndex])
val temp = arr[minIndex]
arr[minIndex] = arr[i]
arr[i] = temp
}
}
fun printArray(arr: IntArray) {
// Loop the item and print each item in the console with white space seperated
val lastIndex: Int = arr.size - 1;
for (i in 0..lastIndex) {
val num = arr[i]
print("$num ")
}
println("")
}
fun main(args: Array<String>) {
val arr: IntArray = intArrayOf(15, 3, 12, 6, -9, 9, 0);
print("Before Sorting: ")
printArray(arr)
selectionSort(arr)
print("After Sorting: ")
printArray(arr)
}
Kotlin Output Screen
Before Sorting: 15 3 12 6 -9 9 0
After Sorting: -9 0 3 6 9 12 15
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