Implement quicksort

This commit is contained in:
Anthony Chan 2017-03-15 00:17:33 -04:00
parent 10c9e6adec
commit c2c6c8b66f

71
Quicksort.java Normal file
View File

@ -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 + " ");
}
}
}