Quick sort implementation

Reviewed-on: Hithomelabs/Princeton1#13
Co-authored-by: hitanshu310 <hitanshu98@gmail.com>
Co-committed-by: hitanshu310 <hitanshu98@gmail.com>

.idea/gradle.xml

@@ -13,6 +13,7 @@
             <option value="$PROJECT_DIR$/module4" />
             <option value="$PROJECT_DIR$/module5" />
             <option value="$PROJECT_DIR$/module6" />
+            <option value="$PROJECT_DIR$/module7" />
           </set>
         </option>
       </GradleProjectSettings>

clients/build.gradle

@@ -15,6 +15,7 @@ dependencies {
     implementation project(':module4')
     implementation project(':module5')
     implementation project(':module6')
+    implementation project(':module7')
     implementation project(':common')
     testImplementation project(':common')
 }

clients/src/main/java/com/hithomelabs/clients/module7/QuickSortClient.java

@@ -0,0 +1,22 @@
+package com.hithomelabs.clients.module7;
+
+import com.hithomelabs.princeton1.common.Apple;
+import com.hithomelabs.princeton1.module7.Quick;
+
+import java.util.Random;
+
+public class QuickSortClient {
+
+    public static void main(String[] args) {
+        int size = 100;
+        Apple[] apples = new Apple[size];
+        Quick<Apple> quick = new Quick<Apple>();
+
+        for (int i = 0; i < apples.length; i++) {
+            apples[i] = new Apple(new Random().nextInt(1000));
+        }
+        quick.sort(apples);
+        for (int i = 0; i < apples.length; i++)
+            System.out.println(apples[i]);
+    }
+}

module7/build.gradle

@@ -0,0 +1,21 @@
+plugins {
+    id 'java'
+}
+
+group = 'com.hithomelabs.princeton1.module7'
+version = 'unspecified'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation platform('org.junit:junit-bom:5.10.0')
+    testImplementation 'org.junit.jupiter:junit-jupiter'
+    implementation project(':module5')
+    testImplementation project(':common')
+}
+
+test {
+    useJUnitPlatform()
+}

module7/src/main/java/com/hithomelabs/princeton1/module7/Quick.java

@@ -0,0 +1,56 @@
+package com.hithomelabs.princeton1.module7;
+
+import com.hithomelabs.princeton1.module5.AbstractCustomSorts;
+
+
+public class Quick<E> extends AbstractCustomSorts<E> {
+    @Override
+    public void sort(E[] arr) {
+        randomShuffle(arr);
+        partition(arr, 0, arr.length-1);
+    }
+
+    private void randomShuffle(E[] arr){
+        int array_len = arr.length;
+        for(int i=0; i< array_len; i++){
+            int random_index = (int)(Math.random()*array_len);
+            exch(arr, i, random_index);
+        }
+    }
+
+    private void partition(E[] arr, int low, int high){
+        if(low >= high)
+            return;
+        int mid = sort(arr, low, high);
+        partition(arr, low, mid-1);
+        partition(arr, mid + 1, high);
+    }
+
+    private int sort(E[] arr, int low, int high){
+        int i = low+1;
+        int j = high;
+        while (true){
+            // Find the i index greater than 1st element
+            while (i<=high && !less((Comparable<E>) arr[low], arr[i]))
+                i++;
+            // Find the j index less than 1st element
+            while (!less((Comparable<E>) arr[j], arr[low]) && j > low)
+                j--;
+            // Break if indexes are crossed
+            if(j <= i)
+                break;
+            // Swap index values of i & j
+            if(less((Comparable<E>) arr[j], arr[i]))
+                exch(arr, i++, j--);
+        }
+        // Swap 1st element to it's correct position
+        int k_index = low+1;
+        while (k_index <= high){
+            if(less((Comparable<E>) arr[low], arr[k_index]))
+                break;
+            k_index++;
+        }
+        exch(arr, low, k_index-1);
+        return k_index - 1;
+    }
+}

module7/src/test/java/com/hithomelabs/princeton1/module7/QuickTest.java

@@ -0,0 +1,60 @@
+package com.hithomelabs.princeton1.module7;
+
+import com.hithomelabs.princeton1.common.Apple;
+import org.junit.jupiter.api.*;
+
+import java.util.ArrayList;
+import java.util.Random;
+import static org.junit.jupiter.api.Assertions.*;
+
+class QuickTest {
+
+    private Quick<Apple> quick;
+    private ArrayList<Apple> apples;
+    private Random random;
+
+    @BeforeEach
+    void setUp() {
+        quick = new Quick<Apple>();
+        apples = new ArrayList<Apple>();
+        random = new Random();
+    }
+
+    @Test
+    @DisplayName("testing Quick sort default implementation")
+    public void testSort(){
+
+        for(int i = 0; i < 100; i++)
+            apples.add(new Apple(random.nextInt(1000)));
+        Apple[] arr = apples.toArray(new Apple[apples.size()]);
+        quick.sort(arr);
+        apples.sort(null);
+        Apple[] sorted =  apples.toArray(new Apple[apples.size()]);
+        Assertions.assertArrayEquals(sorted, arr);
+    }
+
+    // * * Optional test for alternate sort implmentation
+    /*
+    @Test
+    @DisplayName("testing Quick sort default implementation")
+    public void testAltSort(){
+
+        for(int i = 0; i < 100; i++)
+            apples.add(new Apple(random.nextInt(1000)));
+        Apple[] arr = apples.toArray(new Apple[apples.size()]);
+        quick.altSort(arr);
+        apples.sort(null);
+        Apple[] sorted =  apples.toArray(new Apple[apples.size()]);
+        Assertions.assertArrayEquals(sorted, arr);
+    }
+    */
+
+
+
+    @AfterEach
+    void tearDown() {
+        quick = null;
+        apples = null;
+        random = null;
+        }
+}

settings.gradle

@@ -16,4 +16,5 @@ include 'clients'
 include 'module5'
 include 'module6'
 include 'common'
+include 'module7'