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/* sorts.c
*
*
* notes: implement simple hash table, use k&r book
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>
#include <time.h>
#include <assert.h>
#define ARR_SIZE 10
/* function prototypes */
void insrt_sort(int *, int);
void select_sort(int *, int);
void bubble_sort(int *, int);
void prnt_arr(int *, int);
int *mk_rand_arr(int, int);
void mergesort(int *, int, int);
void merge(int *, int, int, int);
/* merge sort, divide and conquer */
void mergesort(int a[], int low, int high)
{
int mid;
if (low < high)
{
mid = (low + high) / 2;
mergesort(a, low, mid);
mergesort(a, mid + 1, high);
merge(a, low, high, mid);
}
}
/* http://en.allexperts.com/q/C-1587/Merge-Sort-C.htm */
void merge(int a[], int low, int high, int mid)
{
int i, j, k, c[50];
i = low;
j = mid + 1;
k = low;
while ( (i <= mid) && (j <= high) )
{
if (a[i] < a[j])
{
c[k] = a[i];
k++;
i++;
}
else
{
c[k] = a[j];
k++;
j++;
}
}
while (i <= mid)
{
c[k] = a[i];
k++;
i++;
}
while (j <= high)
{
c[k] = a[j];
k++;
j++;
}
for (i = low; i < k; i++)
a[i] = c[i];
}
/* in every iteration an element is compared with all the elements before it */
void insrt_sort(int *arr, int elem)
{
int i, j, tmp;
for (i = 1; i < elem; i++)
{
tmp = arr[i];
j = i - 1;
/* tmp is compared to all elements that were already inserted and are in order */
while ( (j >= 0) && (tmp < arr[j]) )
{
arr[j+1] = arr[j];
j--;
}
arr[j+1] = tmp;
}
}
/* slow on nearly sorted array */
void select_sort(int *arr, int elem)
{
int i, j, tmp;
for (i = 0; i < elem - 1; i++)
for (j = i + 1; j < elem; j++)
if (arr[i] > arr[j])
{
tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
}
/* pretty fast on nearly sorted array with extra code */
void bubble_sort(int *arr, int elem)
{
int i, j, tmp;
for (i = 0; i < elem; i++)
for (j = 0; j < elem - i - 1; j++)
{
if (arr[j] > arr[j+1])
{
tmp = arr[j];
arr[j] = arr[j+1];
arr[j+1] = tmp;
}
}
}
void prnt_arr(int *arr, int elem)
{
if (arr == NULL)
fputs("nothing to print", stderr);
int i;
for (i = 0; i < elem; i++)
{
printf("%d ", *(arr + i) );
if ( (i % 10 == 0) && i != 0)
printf("\n");
}
printf("\n");
}
int *mk_rand_arr(int elem, int range)
{
assert(elem > 0);
int *arr = (int *) malloc(sizeof(int) * elem);
if (arr == NULL)
{
perror("malloc");
exit(-1);
}
int i;
range++;
for (i = 0; i < elem; i++)
arr[i] = rand() % range;
return arr;
}
int main(int argc, char **argv)
{
srand( (unsigned int )time(NULL) );
int *arr = mk_rand_arr(ARR_SIZE, 10);
prnt_arr(arr, ARR_SIZE);
//bubble_sort(arr, ARR_SIZE);
//select_sort(arr, ARR_SIZE);
insrt_sort(arr, ARR_SIZE);
prnt_arr(arr, ARR_SIZE);
return 0;
}
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