sort using merge sort code example
Example: Merge sort
class Sort
{
void merge(int arr[], int left, int middle, int right)
{
int low = middle - left + 1; //size of the left subarray
int high = right - middle; //size of the right subarray
int L[] = new int[low]; //create the left and right subarray
int R[] = new int[high];
int i = 0, j = 0;
for (i = 0; i < low; i++) //copy elements into left subarray
{
L[i] = arr[left + i];
}
for (j = 0; j < high; j++) //copy elements into right subarray
{
R[j] = arr[middle + 1 + j];
}
int k = left; //get starting index for sort
i = 0; //reset loop variables before performing merge
j = 0;
while (i < low && j < high) //merge the left and right subarrays
{
if (L[i] <= R[j])
{
arr[k] = L[i];
i++;
}
else
{
arr[k] = R[j];
j++;
}
k++;
}
while (i < low) //merge the remaining elements from the left subarray
{
arr[k] = L[i];
i++;
k++;
}
while (j < high) //merge the remaining elements from right subarray
{
arr[k] = R[j];
j++;
k++;
}
}
void mergeSort(int arr[], int left, int right) //helper function that creates the sub cases for sorting
{
int middle;
if (left < right) { //sort only if the left index is lesser than the right index (meaning that sorting is done)
middle = (left + right) / 2;
mergeSort(arr, left, middle); //left subarray
mergeSort(arr, middle + 1, right); //right subarray
merge(arr, left, middle, right); //merge the two subarrays
}
}
void display(int arr[]) //display the array
{
for (int i=0; i<arr.length; ++i)
{
System.out.print(arr[i]+" ");
}
}
public static void main(String args[])
{
int arr[] = { 9, 3, 1, 5, 13, 12 };
Sort ob = new Sort();
ob.mergeSort(arr, 0, arr.length - 1);
ob.display(arr);
}
}