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MergeSort.java
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100 lines (84 loc) · 2.58 KB
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/**
*
* @author Varun Upadhyay (https://github.com/varunu28)
*
*/
class MergeSort {
/**
* This method implements the Generic 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 right The last index of the array
* Recursively sorts the array in increasing order
**/
public static <T extends Comparable<T>> void MS(T[] arr, T[] temp, int left, int right) {
if (left < right) {
int mid = left + (right - left) / 2;
MS(arr, temp, left, mid);
MS(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
**/
public static <T extends Comparable<T>> void merge(T[] arr, T[] temp, int left, int mid, int right) {
for (int i=left;i<=right;i++) {
temp[i] = arr[i];
}
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];
i++;
}
else {
arr[k] = temp[j];
j++;
}
k++;
}
while (i <= mid) {
arr[k] = temp[i];
i++;
k++;
}
}
// Driver program
public static void main(String[] args) {
// Integer Input
int[] arr = {4,23,6,78,1,54,231,9,12};
Integer[] array = new Integer[arr.length];
for (int i=0;i<array.length;i++) {
array[i] = arr[i];
}
// Copy of actual array
Integer[] temp = new Integer[arr.length];
MS(array, temp, 0, arr.length-1);
// Output => 1 4 6 9 12 23 54 78 231
for (int i=0;i<arr.length;i++) {
System.out.print(array[i] + " ");
}
System.out.println();
// String Input
String[] array1 = {"c", "a", "e", "b","d"};
String[] temp1 = new String[array1.length];
MS(array1, temp1, 0, array1.length-1);
//Output => a b c d e
for(int i=0; i<array1.length; i++)
{
System.out.print(array1[i]+"\t");
}
}
}