quicksort in java

day35/Java/QuickSort.java

@@ -0,0 +1,68 @@
+/**
+ * @date 21/5/21
+ * @author shaybrow
+ */
+
+import java.util.*;
+import static org.junit.Assert.*;
+import org.junit.Test;
+
+public class QuickSort {
+    public static void main(String []args)
+    {
+        Scanner sc=new Scanner(System.in);
+        int n=sc.nextInt();
+        int arr[] = new int[n];
+        for(int i=0;i<arr.length;i++){
+            System.out.println("Enter next int");
+            arr[i]=sc.nextInt();
+
+        }
+        quickSort(arr);
+        for (int i = 0; i < arr.length; i++) {
+            System.out.println(arr[i]);
+        }
+    }
+    public static void quickSort (int [] input){
+        int left = 0;
+        int right = input.length-1;
+        if (left < right){
+            int position =partition(input, left, right);
+
+            quickSort(input, left, position-1);
+            quickSort(input, position+1, right);
+
+        }
+
+    }
+    private static int partition(int[] input, int left, int right){
+
+        int pivot = input[right];
+        int low = left -1;
+        for (int i = left; i <right ; i++) {
+            if (input[i] <= pivot){
+                low ++;
+                swap(input, i, low);
+            }
+        }
+        swap(input, right, low+1);
+        return low + 1;
+    }
+    private static void swap (int [] input, int i, int low){
+        int temp = input[i];
+        input[i] = input[low];
+        input[low] = temp;
+    }
+    public void testQuickSort (){
+        int [] test = {8,4,23,42,16,15};
+        quickSort(test);
+        int [] expect = {4,8,15,16,23,16};
+        assertArrayEquals(expect, test);
+
+        int [] test2 = {100, 75, 50, 25, 0};
+        quickSort(test2);
+        int [] expect2 = {0,25,50,75,100};
+        assertArrayEquals(expect2, test2);
+    }
+
+}

day35/README.md

@@ -44,6 +44,7 @@ output: [1, 2, 3, 4, 5, 6, 7, 8, 9]
 ```js
 to be added
 ```
+### [Java Implementation](./Java/QuickSort.java)
 
 ### [C++ Implementation](./C++/quickSort.cpp)