quick sort premaseem implementation

Author: premaseem

src/me/premaseem/algorithm/quicksort/App.java

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+package me.premaseem.algorithm.quicksort;
+
+import me.premaseem.MyUtils;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class QuickSort {
+    // Test Driven Development by Aseem Jain
+    @Test
+    public void test() {
+        int a2[] = {10, 30, 190, 120, 110, 50, 7};
+
+        sort(a2, 0, 6);
+        MyUtils.isArrSorted(a2);
+    }
+
+
+
+    int partition(int arr[], int low, int high)
+    {
+        int pivot = arr[high];
+        int i = (low-1); // index of smaller element
+        for (int j=low; j<high; j++)
+        {
+            // If current element is smaller than the pivot
+            if (arr[j] < pivot)
+            {
+                i++;
+
+                // swap arr[i] and arr[j]
+                int temp = arr[i];
+                arr[i] = arr[j];
+                arr[j] = temp;
+            }
+        }
+
+        // swap arr[i+1] and arr[high] (or pivot)
+        i++;
+        int temp = arr[i];
+        arr[i] = arr[high];
+        arr[high] = temp;
+
+        return i;
+    }
+
+
+    /* The main function that implements QuickSort()
+      arr[] --> Array to be sorted,
+      low  --> Starting index,
+      high  --> Ending index */
+    void sort(int arr[], int low, int high)
+    {
+        if (low < high)
+        {
+            /* pi is partitioning index, arr[pi] is
+              now at right place */
+            int pi = partition(arr, low, high);
+
+            // Recursively sort elements before
+            // partition and after partition
+            sort(arr, low, pi-1);
+            sort(arr, pi+1, high);
+        }
+    }
+
+}