Java-Algorithms/MergeSort.java at master · m-oito/Java-Algorithms · GitHub

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importjava.util.Scanner;

/**
 * Merge Sort
 *
 */
publicclassMergeSort {
privateint[] array;
privateint[] tempMergArr;
privateintlength;

/**
 * Sorts {@code inputArr} with merge sort algorithm.
 *
 * @param inputArr
 */
publicfinalvoidsort(intinputArr[]) {
this.array = inputArr;
this.length = inputArr.length;
this.tempMergArr = newint[this.length];
this.mergeSort(0, this.length - 1);
 }

/**
 * Partitions Array into recursively smaller pieces.
 *
 * @param lowerIndex
 * lower bound to include in the first partition
 * @param higherIndex
 * upper bound to include in the third partition
 */
privatevoidmergeSort(intlowerIndex, inthigherIndex) {
if (lowerIndex < higherIndex) {
intmiddle = lowerIndex + (higherIndex - lowerIndex) / 2;
// Below step sorts the left side of the array
this.mergeSort(lowerIndex, middle);
// Below step sorts the right side of the array
this.mergeSort(middle + 1, higherIndex);
// Now merge both sides
this.mergeParts(lowerIndex, middle, higherIndex);
 }
 }

/**
 * Merges partitions.
 *
 * @param lowerIndex
 * @param middle
 * @param higherIndex
 */
privatevoidmergeParts(intlowerIndex, intmiddle, inthigherIndex) {
for (inti = lowerIndex; i <= higherIndex; i++) {
this.tempMergArr[i] = this.array[i];
 }
inti = lowerIndex;
intj = middle + 1;
intk = lowerIndex;
while (i <= middle && j <= higherIndex) {
if (this.tempMergArr[i] <= this.tempMergArr[j]) {
this.array[k] = this.tempMergArr[i];
i++;
 } else {
this.array[k] = this.tempMergArr[j];
j++;
 }
k++;
 }
while (i <= middle) {
this.array[k] = this.tempMergArr[i];
k++;
i++;
 }

 }

/**
 * Gets input to sort.
 *
 * @return unsorted array of integers to sort
 */
publicstaticint[] getInput() {
finalintnumElements = 6;
int[] unsorted = newint[numElements];
Scannerinput = newScanner(System.in);
System.out.println("Enter any 6 Numbers for Unsorted Array : ");
for (inti = 0; i < numElements; i++) {
unsorted[i] = input.nextInt();
 }
input.close();
returnunsorted;
 }

/**
 * Main Method.
 *
 * @param args
 */
publicstaticvoidmain(Stringargs[]) {
int[] inputArr = getInput();
MergeSortmergeSort = newMergeSort();
mergeSort.sort(inputArr);
for (inti : inputArr) {
System.out.print(i);
System.out.print(" ");
 }
 }
}