101 lines
2.8 KiB
Java
101 lines
2.8 KiB
Java
package Sorts;
|
|
|
|
import static Sorts.SortUtils.print;
|
|
|
|
/**
|
|
* This method implements the Generic Merge Sort
|
|
*
|
|
* @author Varun Upadhyay (https://github.com/varunu28)
|
|
* @author Podshivalov Nikita (https://github.com/nikitap492)
|
|
* @see SortAlgorithm
|
|
*/
|
|
|
|
class MergeSort implements SortAlgorithm {
|
|
|
|
/**
|
|
* This method implements the Generic Merge Sort
|
|
*
|
|
* @param unsorted the array which should be sorted
|
|
* @param <T> Comparable class
|
|
* @return sorted array
|
|
*/
|
|
@Override
|
|
@SuppressWarnings("unchecked")
|
|
public <T extends Comparable<T>> T[] sort(T[] unsorted) {
|
|
T[] tmp = (T[]) new Comparable[unsorted.length];
|
|
doSort(unsorted, tmp, 0, unsorted.length - 1);
|
|
return unsorted;
|
|
}
|
|
|
|
/**
|
|
* @param arr The array to be sorted
|
|
* @param temp The copy of the actual array
|
|
* @param left The first index of the array
|
|
* @param right The last index of the array
|
|
* Recursively sorts the array in increasing order
|
|
**/
|
|
private static <T extends Comparable<T>> void doSort(T[] arr, T[] temp, int left, int right) {
|
|
if (left < right) {
|
|
int mid = left + (right - left) / 2;
|
|
doSort(arr, temp, left, mid);
|
|
doSort(arr, temp, mid + 1, right);
|
|
merge(arr, temp, left, mid, right);
|
|
}
|
|
|
|
}
|
|
|
|
/**
|
|
* This method implements the merge step of the merge sort
|
|
*
|
|
* @param arr The array to be sorted
|
|
* @param temp The copy of the actual array
|
|
* @param left The first index of the array
|
|
* @param mid The middle index of the array
|
|
* @param right The last index of the array
|
|
* merges two parts of an array in increasing order
|
|
**/
|
|
|
|
private static <T extends Comparable<T>> void merge(T[] arr, T[] temp, int left, int mid, int right) {
|
|
System.arraycopy(arr, left, temp, left, right - left + 1);
|
|
|
|
|
|
int i = left;
|
|
int j = mid + 1;
|
|
int k = left;
|
|
|
|
while (i <= mid && j <= right) {
|
|
if (temp[i].compareTo(temp[j]) <= 0) {
|
|
arr[k++] = temp[i++];
|
|
} else {
|
|
arr[k++] = temp[j++];
|
|
}
|
|
}
|
|
|
|
while (i <= mid) {
|
|
arr[k++] = temp[i++];
|
|
}
|
|
|
|
while (j <= right) {
|
|
arr[k++] = temp[j++];
|
|
}
|
|
}
|
|
|
|
// Driver program
|
|
public static void main(String[] args) {
|
|
|
|
// Integer Input
|
|
Integer[] arr = {4, 23, 6, 78, 1, 54, 231, 9, 12};
|
|
MergeSort mergeSort = new MergeSort();
|
|
mergeSort.sort(arr);
|
|
|
|
// Output => 1 4 6 9 12 23 54 78 231
|
|
print(arr);
|
|
|
|
// String Inpu
|
|
String[] stringArray = {"c", "a", "e", "b", "d"};
|
|
mergeSort.sort(stringArray);
|
|
//Output => a b c d e
|
|
print(stringArray);
|
|
}
|
|
}
|