Merge pull request #1 from SankarshanMishra/SankarshanMishra-patch-1

Create Quicksort

Author: SankarshanMishra

Quicksort

@@ -0,0 +1,78 @@
+// Java program for implementation of QuickSort
+class QuickSort
+{
+	/* This function takes last element as pivot,
+	places the pivot element at its correct
+	position in sorted array, and places all
+	smaller (smaller than pivot) to left of
+	pivot and all greater elements to right
+	of pivot */
+	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 or
+			// equal to 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)
+		int temp = arr[i+1];
+		arr[i+1] = arr[high];
+		arr[high] = temp;
+
+		return i+1;
+	}
+
+
+	/* 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);
+		}
+	}
+
+	/* A utility function to print array of size n */
+	static void printArray(int arr[])
+	{
+		int n = arr.length;
+		for (int i=0; i<n; ++i)
+			System.out.print(arr[i]+" ");
+		System.out.println();
+	}
+
+	// Driver program
+	public static void main(String args[])
+	{
+		int arr[] = {10, 7, 8, 9, 1, 5};
+		int n = arr.length;
+
+		QuickSort ob = new QuickSort();
+		ob.sort(arr, 0, n-1);
+
+		System.out.println("sorted array");
+		printArray(arr);
+	}
+}