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merge-sort.cpp
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merge-sort.cpp
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#include <iostream>
using namespace std;
void merge(int *arr, int l, int m, int r)
{
int i, j, k;
int n1 = m - l + 1;
int n2 = r - m;
cout << l << m << r << n1 << n2 << endl;
int *L = new int[n1], *R = new int[n2];
for (i = 0; i < n1; i++)
L[i] = arr[l + i];
for (j = 0; j < n2; j++)
R[j] = arr[m + 1 + j];
i = 0;
j = 0;
k = l;
while (i < n1 || j < n2)
{
if (j >= n2 || (i < n1 && L[i] <= R[j]))
{
arr[k] = L[i];
i++;
}
else
{
arr[k] = R[j];
j++;
}
k++;
}
delete[] L;
delete[] R;
}
void mergeSort(int *arr, int l, int r, int size)
{
if (l < r)
{
int m = l + (r - l) / 2;
cout << "left" << endl;
mergeSort(arr, l, m, size);
cout << "right" << endl;
mergeSort(arr, m + 1, r, size);
cout << "merge" << endl;
merge(arr, l, m, r);
for (int i = 0; i < size; i++)
cout << arr[i] << " ";
cout << endl;
}
}
void show(int *arr, int size)
{
for (int i = 0; i < size; i++)
cout << arr[i] << " ";
cout << "\n";
}
int main()
{
int size;
cout << "Enter the number of elements : ";
cin >> size;
int *arr = new int[size];
cout << "Enter the unsorted elements : ";
for (int i = 0; i < size; ++i)
{
cin >> arr[i];
}
mergeSort(arr, 0, size - 1, size);
cout << "Sorted array : ";
show(arr, size);
delete[] arr;
return 0;
}