Write a program in c to sort an unsorted array using merge sort method?

Answer 1

#include <stdio.h>

#include <stdlib.h>

#define MAXARRAY 10

void mergesort(int a[], int low, int high);

int main(void) {

int array[MAXARRAY];

int i = 0;

/* load some random values into the array */

for(i = 0; i < MAXARRAY; i++)

array[i] = rand() % 100;

/* array before mergesort */

printf("Before :");

for(i = 0; i < MAXARRAY; i++)

printf(" %d", array[i]);

printf("\n");

mergesort(array, 0, MAXARRAY - 1);

/* array after mergesort */

printf("Mergesort :");

for(i = 0; i < MAXARRAY; i++)

printf(" %d", array[i]);

printf("\n");

return 0;

}

void mergesort(int a[], int low, int high) {

int i = 0;

int length = high - low + 1;

int pivot = 0;

int merge1 = 0;

int merge2 = 0;

int working[length];

if(low == high)

return;

pivot = (low + high) / 2;

mergesort(a, low, pivot);

mergesort(a, pivot + 1, high);

for(i = 0; i < length; i++)

working[i] = a[low + i];

merge1 = 0;

merge2 = pivot - low + 1;

for(i = 0; i < length; i++) {

if(merge2 <= high - low)

if(merge1 <= pivot - low)

if(working[merge1] > working[merge2])

a[i + low] = working[merge2++];

else

a[i + low] = working[merge1++];

else

a[i + low] = working[merge2++];

else

a[i + low] = working[merge1++];

}

}