Merge-sort Source-Code

November 27th, 2007

Filed under: Algorithms — Unggul_USA @ 2:22 pm — View blog reactions

#include
#include
#define NUM_ITEMS 100
void mergeSort(int numbers[], int temp[], int array_size);
void m_sort(int numbers[], int temp[], int left, int right);
void merge(int numbers[], int temp[], int left, int mid, int right);
int numbers[NUM_ITEMS];
int temp[NUM_ITEMS];
int counter;
int main()
{
int i; //seed random number generator
srand(getpid()); //fill array with random integers
for (i = 0; i < NUM_ITEMS; i++)
numbers[i] = rand();
mergeSort(numbers, temp, NUM_ITEMS); //perform merge sort on array
for (i = 0; i < NUM_ITEMS; i++)
printf("%i\n", numbers[i]);
printf("Done with sort.\n");
printf("%i %i\n", i, counter);
}

void mergeSort(int numbers[], int temp[], int array_size)
{
m_sort(numbers, temp, 0, array_size - 1);
}

void m_sort(int numbers[], int temp[], int left, int right)
{
int mid;
if (right > left)
{
mid = (right + left) / 2;
m_sort(numbers, temp, left, mid);
m_sort(numbers, temp, mid+1, right);
merge(numbers, temp, left, mid+1, right);
}
counter++;
}

void merge(int numbers[], int temp[], int left, int mid, int right)
{
int i, left_end, num_elements, tmp_pos;
left_end = mid - 1;
tmp_pos = left;
num_elements = right - left + 1;
while ((left <= left_end) && (mid <= right))
{
if (numbers[left] <= numbers[mid])
{
temp[tmp_pos] = numbers[left];
tmp_pos = tmp_pos + 1;
left = left +1;
}
else
{
temp[tmp_pos] = numbers[mid];
tmp_pos = tmp_pos + 1;
mid = mid + 1;
}
counter++;
}
while (left <= left_end)
{
temp[tmp_pos] = numbers[left];
left = left + 1;
tmp_pos = tmp_pos + 1;
counter++;
}
while (mid <= right)
{
temp[tmp_pos] = numbers[mid];
mid = mid + 1;
tmp_pos = tmp_pos + 1;
counter++;
}
for (i=0; i <= num_elements; i++)
{
numbers[right] = temp[right];
right = right - 1;
counter++;
}
}