QuickSort.java Implemented QuickSort in java.

This adds QuickSort Algorithm which return the concatenation of the
quicksorted list of elements that are less than or equal to the pivot, the
pivot, and the quicksorted list of elements that are greater than the pivot.

Closes #150

merge_sort/Java/QuickSort.java

@@ -0,0 +1,47 @@
+package lecture9;
+
+public class QuickSort {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		Scanner s = new Scanner(System.in);
+		System.out.println("Enter size: ");
+		int n = s.nextInt();
+		int[] arr = new int[n];
+		System.out.println("Enter elements: ");
+		for (int i = 0; i < n; i++) {
+			arr[i] = s.nextInt();
+		}
+        quicksort(arr,0,arr.length-1);
+        for(int i=0;i<arr.length;i++){
+        	System.out.print(arr[i]+" ");
+        }
+	}
+	public static void quicksort(int arr[],int low, int high){
+		if(low>=high){
+			return;
+		}
+		int left=low;
+		int right=high;
+		int mid=(low+high)/2;
+		int pivot=arr[mid];
+		while(left<=right){
+			while(arr[left]<pivot){
+				left++;
+			}
+			while(arr[right]>pivot){
+				right--;
+			}
+			if(left<=right){
+				int temp=arr[left];
+				arr[left]=arr[right];
+				arr[right]=temp;
+				left++;
+				right--;
+				}
+		}
+		quicksort(arr,low,right);
+		quicksort(arr,left,high);
+	}
+
+}