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SortedArray.kt
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SortedArray.kt
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/*******************************************************
* SortedArray.kt
* Created by Stephen Hall on 11/08/18.
* Copyright (c) 2018 Stephen Hall. All rights reserved.
* SortedArray implementation in Kotlin
*******************************************************/
/**
* SortedArray Class
* @param <T> Generic type</T>
*/
class SortedArray<T : Comparable<T?>>
/**
* SortedArray constructor initialized to a specific size
* @param size Size to initialize the array to
*/
(size: Int) {
/**
* Private Members
*/
var array: Array<T?>
var count: Int = 0
var size: Int = 0
/**
* SortedArray default constructor
*/
constructor() : this(4) {}
init {
count = 0
if (size > 0)
this.size = size
else
this.size = 4
array = arrayOfNulls<Comparable<*>>(this.size) as Array<T?>
}
/**
* Doubles the size of the internal array
*/
private fun resize() {
size *= 2
val tmp = arrayOfNulls<Comparable<*>>(size) as Array<T?>
System.arraycopy(array!!, 0, tmp, 0, count)
array = tmp
}
/**
* Adds new item into the array
* @param data Data to add into the array
* @return Data added into the array
*/
fun add(data: T?): T? {
if (data == null)
return null
if (this.count == size)
resize()
array[count] = data
count++
return data
}
/**
* Appends the contents of an array to the SortedArray
* @param data: array to append
* @return boolean: success|fail
*/
fun append(data: Array<T?>): Boolean {
if (data != null) {
for (aData in data) {
if (aData != null)
add(aData)
}
return true
}
return false
}
/**
* Sets the data at the given index
* @param index: index to set
* @param data: data to set index to
* @return boolean: success|fail
*/
operator fun set(index: Int, data: T): Boolean {
if (index >= 0 && index < size) {
array[index] = data
return true
}
return false
}
/**
* Gets the data at the arrays given index
* @param index Index to get data at
* @return Data at the given index or default value of T if index does not exist
*/
operator fun get(index: Int): T? {
return if (index in 0..(size - 1)) array[index] else null
}
/**
* Removes the data at arrays given index
* @param index Index to remove
* @return Data removed from the array or default T value if index does not exist
*/
fun remove(index: Int): T? {
if (index < 0 || index > count)
return null
val tmp = array[index]
array[index] = null
count--
return tmp
}
/**
* Resets the internal array to default size with no data
*/
fun reset() {
count = 0
size = 4
array = arrayOfNulls<Comparable<*>>(this.size) as Array<T?>
}
/**
* Clears all data in the array leaving size intact
*/
fun clear() {
for (i in 0 until count) {
array[i] = null
}
this.count = 0
}
/**
* Gets the current count of the array
* @return Number of items in the array
*/
fun count(): Int {
return count
}
/**
* Private helper method for Merger Sort. Merges two sub-arrays of arr[].
* @param arr: array to be sorted
* @param l: index of first sub array
* @param m: merge point
* @param r: index of second sub array
*/
private fun merge(arr: Array<T?>, l: Int, m: Int, r: Int) {
var i: Int
var j: Int
var k: Int
val n1 = m - l + 1
val n2 = r - m
// create temp arrays
val L = arrayOfNulls<Comparable<*>>(n1) as Array<T?>
val R = arrayOfNulls<Comparable<*>>(n2) as Array<T?>
// Copy data to temp arrays L[] and R[]
i = 0
while (i < n1) {
L[i] = arr[l + i]
i++
}
j = 0
while (j < n2) {
R[j] = arr[m + 1 + j]
j++
}
// Merge the temp arrays back into arr[l..r]
i = 0 // Initial index of first sub-array
j = 0 // Initial index of second sub-array
k = l // Initial index of merged sub-array
while (i < n1 && j < n2) {
if (lessThan(L[i], R[j]) || equalTo(L[i], R[j])) {
arr[k] = L[i]
i++
} else {
arr[k] = R[j]
j++
}
k++
}
// Copy the remaining elements of L[], if there are any
while (i < n1) {
arr[k] = L[i]
i++
k++
}
// Copy the remaining elements of R[], if there are any
while (j < n2) {
arr[k] = R[j]
j++
k++
}
}
/**
* Recursive helper method for merge sort
* @param arr: sub array to be sorted
* @param l: left index
* @param r: right index
*/
private fun mergeSortHelper(arr: Array<T?>, l: Int, r: Int) {
if (l < r) {
// Same as (l+r)/2, but avoids overflow for
// large l and h
val m = l + (r - l) / 2
// Sort first and second halves
mergeSortHelper(arr, l, m)
mergeSortHelper(arr, m + 1, r)
merge(arr, l, m, r)
}
}
/**
* Performs Merge Sort on internal array
* @return T[]: sorted copy of the internal array
*/
fun mergeSort(): Array<T?> {
val tmp = arrayOfNulls<Comparable<*>>(count) as Array<T?>
System.arraycopy(array, 0, tmp, 0, count)
mergeSortHelper(tmp, 0, count - 1)
return tmp
}
/**
* Performs Bubble sort on internal array
* @return T[]: sorted copy of the internal array
*/
fun bubbleSort(): Array<T?> {
val tmp = arrayOfNulls<Comparable<T?>>(count) as Array<T?>
System.arraycopy(array, 0, tmp, 0, count)
for (i in 0 until count - 1)
for (j in 0 until count - i - 1) {
if (greaterThan(tmp[j], tmp[j + 1])) {
// swap temp and arr[i]
val temp = tmp[j]
tmp[j] = tmp[j + 1]
tmp[j + 1] = temp
}
}
return tmp
}
/**
* Helper method for Quick Sort. Swaps data in the partition
* @param arr: array to be sorted
* @param low: low index
* @param high: high index
* @return int: pivot index
*/
private fun partition(arr: Array<T?>, low: Int, high: Int): Int {
val pivot = arr[high]
var i = low - 1 // index of smaller element
for (j in low until high) {
// If current element is smaller than or
// equal to pivot
if (lessThan(arr[j], pivot) || equalTo(arr[j], pivot)) {
i++
// swap arr[i] and arr[j]
val temp = arr[i]
arr[i] = arr[j]
arr[j] = temp
}
}
// swap arr[i+1] and arr[high] (or pivot)
val temp = arr[i + 1]
arr[i + 1] = arr[high]
arr[high] = temp
return i + 1
}
/**
* Helper method for recursive Quick Sort
* @param arr: array to be sorted
* @param low: low index
* @param high: high index
*/
private fun quickSortHelper(arr: Array<T?>, low: Int, high: Int) {
if (low < high) {
// pivot is partitioning index, arr[pivot] is now at right place
val pivot = partition(arr, low, high)
// Recursively sort elements before and after pivot
quickSortHelper(arr, low, pivot - 1)
quickSortHelper(arr, pivot + 1, high)
}
}
/**
* Performs Quick Sort on the internal array
* @return T[]: sorted copy of the internal array
*/
fun quickSort(): Array<T?> {
val tmp = arrayOfNulls<Comparable<T?>>(count) as Array<T?>
System.arraycopy(array, 0, tmp, 0, count)
quickSortHelper(tmp, 0, count - 1)
return tmp
}
/**
* Performs Insertion sort on the internal array
* @return T[]: sorted copy of the internal array
*/
fun insertionSort(): Array<T?> {
val tmp = arrayOfNulls<Comparable<T?>>(count) as Array<T?>
System.arraycopy(array, 0, tmp, 0, count)
for (i in 1 until count) {
val key = tmp[i]
var j = i - 1
// Move elements of arr[0..i-1], that are greater than key, to one position ahead
while (j >= 0 && lessThan(tmp[j], key)) {
tmp[j + 1] = tmp[j]
j = j - 1
}
tmp[j + 1] = key
}
return tmp
}
/**
* Performs Selection Sort on internal array
* @return T[]: Sorted copy of the internal data
*/
fun selectionSort(): Array<T?> {
val tmp = arrayOfNulls<Comparable<T?>>(count) as Array<T?>
System.arraycopy(array, 0, tmp, 0, count)
// One by one move boundary of unsorted sub-array
for (i in 0 until count - 1) {
// Find the minimum element in unsorted array
var min = i
for (j in i + 1 until count)
if (lessThan(tmp[j], tmp[min]))
min = j
// Swap the found minimum element with the first
// element
val temp = tmp[min]
tmp[min] = tmp[i]
tmp[i] = temp
}
return tmp
}
/**
* Determines if a is less than b
* @param a: generic type to test
* @param b: generic type to test
* @return boolean: true|false
*/
private fun lessThan(a: T?, b: T?): Boolean {
return a!!.compareTo(b) < 0
}
/**
* Determines if a is equal to b
* @param a: generic type to test
* @param b: generic type to test
* @return boolean: true|false
*/
private fun equalTo(a: T?, b: T?): Boolean {
return a!!.compareTo(b) == 0
}
/**
* Determines if a is greater than b
* @param a: generic type to test
* @param b: generic type to test
* @return boolean: true|false
*/
private fun greaterThan(a: T?, b: T?): Boolean {
return a!!.compareTo(b) > 0
}
}