Quicksort in Java Added

Author: Jatin-Madaan

classical_algorithms/QuickSort.java

@@ -0,0 +1,33 @@
+public class QuickSort{
+
+    public static int partition(int[] arr, int low, int high){
+        int pivot = arr[high]; // taking pivot at rightmost pos
+        int start_ptr = low - 1;
+        for(int i = low; i < high; i++){
+            if(arr[i] < pivot){
+                start_ptr++;
+                
+                int tmp = arr[i];
+                arr[i] = arr[start_ptr];
+                arr[start_ptr] = tmp;
+            }
+        }
+
+        // swaping the last element i.e. "pivot"
+        int temp = arr[high];
+        arr[high] = arr[start_ptr + 1];
+        arr[start_ptr + 1] = temp;
+
+        return start_ptr + 1;
+    }
+
+    public static void sort(int[] arr, int low, int high){
+        if(low < high){
+            int pi_index = partition(arr, low,high);
+            
+            partition(arr, low, pi_index - 1);
+            partition(arr, pi_index + 1, high);
+        }
+    }
+
+}