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package com.sorts;
import static com.sorts.SortUtils.less;
import static com.sorts.SortUtils.swap;
public class QuickSort {
/**
* This method implements the Generic Quick Sort
*
* @param array The array to be sorted
* Sorts the array in increasing order
**/
public <T extends Comparable<T>> T[] sort(T[] array) {
doSort(array, 0, array.length - 1);
return array;
}
/**
* The sorting process
*
* @param left The first index of an array
* @param right The last index of an array
* @param array The array to be sorted
**/
private static <T extends Comparable<T>> void doSort(T[] array, int left, int right) {
if (left < right) {
int pivot = partition(array, left, right);
doSort(array, left, pivot - 1);
doSort(array, pivot, right);
}
}
/**
* This method finds the partition index for an array
*
* @param array The array to be sorted
* @param left The first index of an array
* @param right The last index of an array
* Finds the partition index of an array
**/
private static <T extends Comparable<T>> int partition(T[] array, int left, int right) {
int mid = (left + right) / 2;
T pivot = array[mid];
while (left <= right) {
while (less(array[left], pivot)) {
++left;
}
while (less(pivot, array[right])) {
--right;
}
if (left <= right) {
swap(array, left, right);
++left;
--right;
}
}
return left;
}
}