quick sort code in java
import java.util.*;
class QuickSort {
//selects last element as pivot, pi using which array is partitioned.
int partition(int intArray[], int low, int high) {
int pi = intArray[high];
int i = (low-1); // smaller element index
for (int j=low; j<high; j++) {
// check if current element is less than or equal to pi
if (intArray[j] <= pi) {
i++;
// swap intArray[i] and intArray[j]
int temp = intArray[i];
intArray[i] = intArray[j];
intArray[j] = temp;
}
}
// swap intArray[i+1] and intArray[high] (or pi)
int temp = intArray[i+1];
intArray[i+1] = intArray[high];
intArray[high] = temp;
return i+1;
}
//routine to sort the array partitions recursively
void quick_sort(int intArray[], int low, int high) {
if (low < high) {
//partition the array around pi=>partitioning index and return pi
int pi = partition(intArray, low, high);
// sort each partition recursively
quick_sort(intArray, low, pi-1);
quick_sort(intArray, pi+1, high);
}
}
}
class QUICK_SORT{
public static void main(String args[]) {
//initialize a numeric array, intArray
int intArray[] = {3,2,1,6,5,4};
int n = intArray.length;
//print the original array
System.out.println("Original Array: " + Arrays.toString(intArray));
//call quick_sort routine using QuickSort object
QuickSort obj = new QuickSort();
obj.quick_sort(intArray, 0, n-1);
//print the sorted array
System.out.println("\nSorted Array: " + Arrays.toString(intArray));
}
}