forked from TheAlgorithms/Java
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathMergeSort.java
More file actions
107 lines (100 loc) · 2.97 KB
/
Copy pathMergeSort.java
File metadata and controls
107 lines (100 loc) · 2.97 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
import java.util.Scanner;
/**
* Merge Sort
*
*/
public class MergeSort {
private int[] array;
private int[] tempMergArr;
private int length;
/**
* Sorts {@code inputArr} with merge sort algorithm.
*
* @param inputArr
*/
public final void sort(int inputArr[]) {
this.array = inputArr;
this.length = inputArr.length;
this.tempMergArr = new int[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
*/
private void mergeSort(int lowerIndex, int higherIndex) {
if (lowerIndex < higherIndex) {
int middle = 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
*/
private void mergeParts(int lowerIndex, int middle, int higherIndex) {
for (int i = lowerIndex; i <= higherIndex; i++) {
this.tempMergArr[i] = this.array[i];
}
int i = lowerIndex;
int j = middle + 1;
int k = 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
*/
public static int[] getInput() {
final int numElements = 6;
int[] unsorted = new int[numElements];
Scanner input = new Scanner(System.in);
System.out.println("Enter any 6 Numbers for Unsorted Array : ");
for (int i = 0; i < numElements; i++) {
unsorted[i] = input.nextInt();
}
input.close();
return unsorted;
}
/**
* Main Method.
*
* @param args
*/
public static void main(String args[]) {
int[] inputArr = getInput();
MergeSort mergeSort = new MergeSort();
mergeSort.sort(inputArr);
for (int i : inputArr) {
System.out.print(i);
System.out.print(" ");
}
}
}