Create quicksort.java

quicksort.java

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+// Java implementation of QuickSort
+import java.io.*;
+
+class GFG{
+
+// A utility function to swap two elements
+static void swap(int[] arr, int i, int j)
+{
+	int temp = arr[i];
+	arr[i] = arr[j];
+	arr[j] = temp;
+}
+
+/* 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 */
+static int partition(int[] arr, int low, int high)
+{
+
+	// pivot
+	int pivot = arr[high];
+
+	// Index of smaller element and
+	// indicates the right position
+	// of pivot found so far
+	int i = (low - 1);
+
+	for(int j = low; j <= high - 1; j++)
+	{
+
+		// If current element is smaller
+		// than the pivot
+		if (arr[j] < pivot)
+		{
+
+			// Increment index of
+			// smaller element
+			i++;
+			swap(arr, i, j);
+		}
+	}
+	swap(arr, i + 1, high);
+	return (i + 1);
+}
+
+/* The main function that implements QuickSort
+		arr[] --> Array to be sorted,
+		low --> Starting index,
+		high --> Ending index
+*/
+static void quickSort(int[] arr, int low, int high)
+{
+	if (low < high)
+	{
+
+		// pi is partitioning index, arr[p]
+		// is now at right place
+		int pi = partition(arr, low, high);
+
+		// Separately sort elements before
+		// partition and after partition
+		quickSort(arr, low, pi - 1);
+		quickSort(arr, pi + 1, high);
+	}
+}
+
+// Function to print an array
+static void printArray(int[] arr, int size)
+{
+	for(int i = 0; i < size; i++)
+		System.out.print(arr[i] + " ");
+
+	System.out.println();
+}
+
+// Driver Code
+public static void main(String[] args)
+{
+	int[] arr = { 10, 7, 8, 9, 1, 5 };
+	int n = arr.length;
+
+	quickSort(arr, 0, n - 1);
+	System.out.println("Sorted array: ");
+	printArray(arr, n);
+}
+}
+
+// This code is contributed by Ayush Choudhary