Александр Дубровский dubrovv@@kkyy @end|ng |rom gm@||@com
Sat Dec 14 21:37:59 CET 2019

```/* Iterative C program for merge sort */
#include<stdlib.h>
#include<stdio.h>

/* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[]
*/
void merge(int arr[], int l, int m, int r);

// Utility function to find minimum of two integers
int min(int x, int y) { return (x<y)? x :y; }

/* Iterative mergesort function to sort arr[0...n-1] */
void mergeSort(int arr[], int n)
{
int curr_size;  // For current size of subarrays to be merged
// curr_size varies from 1 to n/2
int left_start; // For picking starting index of left subarray
// to be merged

// Merge subarrays in bottom up manner.  First merge subarrays of
// size 1 to create sorted subarrays of size 2, then merge subarrays
// of size 2 to create sorted subarrays of size 4, and so on.
for (curr_size=1; curr_size<=n-1; curr_size = 2*curr_size)
{
// Pick starting point of different subarrays of current size
for (left_start=0; left_start<n-1; left_start += 2*curr_size)
{
// Find ending point of left subarray. mid+1 is starting
// point of right
int mid = min(left_start + curr_size - 1, n-1);

int right_end = min(left_start + 2*curr_size - 1, n-1);

// Merge Subarrays arr[left_start...mid] &
arr[mid+1...right_end]
merge(arr, left_start, mid, right_end);
}
}
}

/* Function to merge the two haves arr[l..m] and arr[m+1..r] of array arr[]
*/
void merge(int arr[], int l, int m, int r)
{
int i, j, k;
int n1 = m - l + 1;
int n2 =  r - m;

/* create temp arrays */
int L[n1], R[n2];

/* Copy data to temp arrays L[] and R[] */
for (i = 0; i < n1; i++)
L[i] = arr[l + i];
for (j = 0; j < n2; j++)
R[j] = arr[m + 1+ j];

/* Merge the temp arrays back into arr[l..r]*/
i = 0;
j = 0;
k = l;
while (i < n1 && j < n2)
{
if (L[i] <= R[j])
{
arr[k] = L[i];
i++;
}
else
{
arr[k] = R[j];
j++;
}
k++;
}

/* Copy the remaining elements of L[], if there are any */
while (i < n1)
{
arr[k] = L[i];
i++;
k++;
}

/* Copy the remaining elements of R[], if there are any */
while (j < n2)
{
arr[k] = R[j];
j++;
k++;
}
}

/* Function to print an array */
void printArray(int A[], int size)
{
int i;
for (i=0; i < size; i++)
printf("%d ", A[i]);
printf("\n");
}

/* Driver program to test above functions */
int main()
{
int arr[] = {12, 11, 13, 5, 6, 7};
int n = sizeof(arr)/sizeof(arr[0]);

printf("Given array is \n");
printArray(arr, n);

mergeSort(arr, n);

printf("\nSorted array is \n");
printArray(arr, n);
return 0;
}

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