add sorting algorithms

- edit mergesort
- add quicksort
- add countingsort

src/main/kotlin/it/norangeb/algorithms/sorting/Countingsort.kt

@@ -0,0 +1,51 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.sorting
+
+object Countingsort {
+
+    fun sort(array: Array<Int>, from: Int, to: Int) {
+        if (from >= to)
+            return
+
+        val range = to - from + 1
+
+        val bucket = Array(range) { 0 }
+
+        array.forEach { bucket[it - from] += 1 }
+
+        bucket.forEachIndexed { index, i ->
+            if (index != 0) {
+                bucket[index] += bucket[index - 1]
+            }
+        }
+        val aux = array.clone()
+
+        aux.forEach {
+            array[--bucket[it - from]] = it
+        }
+    }
+}

src/main/kotlin/it/norangeb/algorithms/sorting/Mergesort.kt

@@ -27,13 +27,13 @@ package it.norangeb.algorithms.sorting
 
 object Mergesort : Sorter() {
     override fun <T> sort(array: Array<T>, isLess: (T, T) -> Boolean) {
-        val auxiliary = arrayOfNulls<Any>(array.size) as Array<T>
-        sort(array, auxiliary, 0, array.size - 1, isLess)
+        val aux = array.clone()
+        sort(array, aux, 0, array.size - 1, isLess)
     }
 
     private fun <T> sort(
         array: Array<T>,
-        auxiliary: Array<T>,
+        aux: Array<T>,
         low: Int,
         high: Int,
         isLess: (T, T) -> Boolean
@@ -42,35 +42,36 @@ object Mergesort : Sorter() {
 
         val mid = low + (high - low) / 2
 
-        sort(array, auxiliary, low, mid, isLess)
-        sort(array, auxiliary, mid + 1, high, isLess)
+        sort(array, aux, low, mid, isLess)
+        sort(array, aux, mid + 1, high, isLess)
 
-        if (!isLess(array[mid+1], array[mid]))
+        if (isLess(array[mid], array[mid + 1]))
             return
 
-        merge(array, auxiliary, low, mid, high, isLess)
+        merge(array, aux, low, mid, high, isLess)
     }
 
-    private inline fun <T> merge(
+    private fun <T> merge(
         array: Array<T>,
-        auxiliary: Array<T>,
+        aux: Array<T>,
         low: Int,
         mid: Int,
         high: Int,
         isLess: (T, T) -> Boolean
     ) {
+
         for (i in low..high)
-            auxiliary[i] = array[i]
+            aux[i] = array[i]
 
         var i = low
         var j = mid + 1
 
         for (k in low..high)
             when {
-                i > mid -> array[k] = auxiliary[j++]
-                j > high -> array[k] = auxiliary[i++]
-                isLess(auxiliary[j], auxiliary[i]) -> array[k] = auxiliary[j++]
-                else -> array[k] = auxiliary[i++]
+                i > mid -> array[k] = aux[j++]
+                j > high -> array[k] = aux[i++]
+                isLess(aux[i], aux[j]) -> array[k] = aux[i++]
+                else -> array[k] = aux[j++]
             }
     }
 }

src/main/kotlin/it/norangeb/algorithms/sorting/Quicksort.kt

@@ -0,0 +1,74 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.sorting
+
+object Quicksort : Sorter() {
+    override fun <T> sort(array: Array<T>, isLess: (T, T) -> Boolean) {
+        sort(array, 0, array.size - 1, isLess)
+    }
+
+    private fun <T> sort(array: Array<T>, low: Int, high: Int, isLess: (T, T) -> Boolean) {
+        if (low >= high)
+            return
+
+        val mid = partitioning(array, low, high, isLess)
+
+        sort(array, low, mid - 1, isLess)
+        sort(array, mid + 1, high, isLess)
+    }
+
+    private fun <T> partitioning(
+        array: Array<T>,
+        low: Int,
+        high: Int,
+        isLess: (T, T) -> Boolean
+    ): Int {
+        var i = low
+        var j = high + 1
+
+        while (true) {
+            while (isLess(array[++i], array[low]))
+                if (i == high) break
+
+            while (isLess(array[low], array[--j]))
+                if (j == low) break
+
+            if (i >= j) break
+
+            swap(array, i, j)
+        }
+
+        swap(array, low, j)
+
+        return j
+    }
+
+    private fun <T> swap(array: Array<T>, i: Int, j: Int) {
+        val tmp = array[i]
+        array[i] = array[j]
+        array[j] = tmp
+    }
+}

src/test/kotlin/it/norangeb/algorithms/sorting/CountingsortTest.kt

@@ -0,0 +1,43 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.sorting
+
+import org.amshove.kluent.`should equal`
+import org.junit.jupiter.api.Test
+
+class CountingsortTest {
+
+    @Test
+    fun testSort() {
+        val array = arrayOf(13, 15, 11, 4, 5, 3, 2, 7, 1, 2, 3, 3, 6, 9, 11)
+        val arrayCopy = array.clone()
+
+        Countingsort.sort(array, 1, 15)
+
+        array `should equal` arrayCopy.sortedArray()
+    }
+}
+

src/test/kotlin/it/norangeb/algorithms/sorting/QuicksortTest.kt

@@ -0,0 +1,64 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.sorting
+
+import org.amshove.kluent.`should equal`
+import org.junit.jupiter.api.Test
+
+class QuicksortTest {
+
+    @Test
+    fun testSort() {
+        val array = arrayOf(5, 2, 3, 1, 4)
+        val arrayCopy = array.clone()
+
+        Quicksort.sort(array)
+
+        array `should equal` arrayCopy.sortedArray()
+    }
+
+    @Test
+    fun testSortBy() {
+        val array = arrayOf(5, 2, 1, 4, 3, 23, 12, 1, 89, 7)
+        val arrayCopy = array.clone()
+
+        Quicksort.sortBy(array) { it }
+
+        array `should equal` arrayCopy.sortedArray()
+    }
+
+    @Test
+    fun testSortWith() {
+        val array = arrayOf(4, 5, 3, 2, 1)
+        val arrayCopy = array.clone()
+
+        Quicksort.sortWith(array) { t1, t2 ->
+            t1.compareTo(t2)
+        }
+
+        array `should equal` arrayCopy.sortedArray()
+    }
+}