Implement quicksort

anthonyc1 · anthonyc1 · commit c2c6c8b66f22 · 2017-03-15T00:17:33.000-04:00
diff --git a/Quicksort.java b/Quicksort.java
@@ -0,0 +1,71 @@
+import java.util.Scanner;
+
+public class Quicksort{
+
+	public static void main(String[] args){
+		Scanner input = new Scanner(System.in);
+		int[] array;
+		int size = 0;
+
+		//Prompt user to create array and its elements
+		System.out.print("Enter the size of the array: ");
+		size = input.nextInt();
+		array = new int[size];
+		for (int i = 0; i < size; i++){
+			System.out.print("For index " + i + ", give an integer input: ");
+			array[i] = input.nextInt();
+		}
+
+		//Output inputted array
+		System.out.println("The array is: ");
+		printarray(array);
+		System.out.println();
+
+		//Run quicksort, and output sorted array
+		quicksort(array, 0, array.length - 1);
+		System.out.println("The sorted array is: ");
+		printarray(array);
+		System.out.println();
+	}
+	
+	//Quicksort Method
+	public static void quicksort(int[] ar, int start, int end){
+		int[] array;
+		
+		int i = start, j = end;
+		if (end-start >= 1){
+			int pivot = ar[end];
+			while (i< j){
+				while (ar[i]<pivot && i<end){
+					i++;
+				}
+				while (ar[j]>=pivot && j>start){
+					j--;
+				}
+				if (i<j){
+					swap(ar, i, j);
+				}
+			} swap(ar, end, i);
+
+			quicksort(ar, start, i-1);
+			quicksort(ar, i+1, end);
+		} else{
+			return;
+		}
+	}
+
+	//Helper methods
+	public static void swap(int[] ar, int index1, int index2){
+
+		int temp = ar[index1];
+		ar[index1] = ar[index2];
+		ar[index2] = temp;
+	}
+
+	public static void printarray(int[] array){
+
+		for (int data : array){
+			System.out.print(data + " ");
+		}
+	}
+}
