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QuickSort.java
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105 lines (86 loc) · 2.84 KB
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package Sorts;
import static Sorts.SortUtils.*;
/**
* @author Varun Upadhyay (https://github.com/varunu28)
* @author Podshivalov Nikita (https://github.com/nikitap492)
* @see SortAlgorithm
*/
class QuickSort implements SortAlgorithm {
/**
* This method implements the Generic Quick Sort
*
* @param array The array to be sorted
* Sorts the array in increasing order
**/
@Override
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 = randomPartition(array, left, right);
doSort(array, left, pivot - 1);
doSort(array, pivot, right);
}
}
/**
* Ramdomize the array to avoid the basically ordered sequences
*
* @param array The array to be sorted
* @param left The first index of an array
* @param right The last index of an array
* @return the partition index of the array
*/
private static <T extends Comparable<T>> int randomPartition(T[] array, int left, int right) {
int randomIndex = left + (int)(Math.random()*(right - left + 1));
swap(array, randomIndex, right);
return partition(array, left, 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;
}
// Driver Program
public static void main(String[] args) {
// For integer input
Integer[] array = {3, 4, 1, 32, 0, 1, 5, 12, 2, 5, 7, 8, 9, 2, 44, 111, 5};
QuickSort quickSort = new QuickSort();
quickSort.sort(array);
//Output => 0 1 1 2 2 3 4 5 5 5 7 8 9 12 32 44 111
print(array);
String[] stringArray = {"c", "a", "e", "b", "d"};
quickSort.sort(stringArray);
//Output => a b c d e
print(stringArray);
}
}