added sorting algo QuickSort

deepakumarvu · deepakumarvu · commit 154dc2ae7975 · 2019-10-13T12:12:41.000+05:30
diff --git a/Sorting Algorithms/QuickSort.java b/Sorting Algorithms/QuickSort.java
@@ -0,0 +1,77 @@
+// 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 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) 
+		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); 
+	}
+} 
