Created
March 17, 2012 11:19
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#include <stdlib.h> | |
#include <string.h> | |
#include <malloc.h> | |
/* merge sort in N*2 space. */ | |
static void | |
mergesort_impl (int *intv, | |
int *tmp, | |
int count) | |
{ | |
if (count == 2) { | |
if (intv[0] > intv[1]) { | |
int tmp; | |
tmp = intv[0]; | |
intv[0] = intv[1]; | |
intv[1] = tmp; | |
} | |
} else if (count > 2) { | |
int alen, blen; | |
int ia, ib, i; | |
int *a, *b; | |
alen = count / 2; | |
blen = (count + 1) / 2; | |
memcpy (tmp, intv, sizeof (int) * count); | |
a = &tmp[0]; | |
b = &tmp[alen]; | |
mergesort_impl (a, &intv[0], alen); | |
mergesort_impl (b, &intv[alen], blen); | |
i = 0; | |
ia = 0; | |
ib = 0; | |
while (ia < alen && ib < blen) { | |
if (a[ia] < b[ib]) { | |
intv[i] = a[ia]; | |
++ia; | |
} else { | |
intv[i] = b[ib]; | |
++ib; | |
} | |
++i; | |
} | |
if (ia < alen) | |
memcpy (&intv[i], &a[ia], sizeof (int) * (alen - ia)); | |
if (ib < blen) | |
memcpy (&intv[i], &b[ib], sizeof (int) * (blen - ib)); | |
} | |
} | |
static void | |
mergesort (int *intv, | |
int count) | |
{ | |
int *tmp; | |
tmp = malloc (sizeof (int) * count); | |
mergesort_impl (intv, tmp, count); | |
free (tmp); | |
} | |
int | |
main (int argc, | |
char **argv) | |
{ | |
int i; | |
int *numbers; | |
argc --; | |
argv ++; | |
numbers = malloc (sizeof (int) * argc); | |
for (i = 0; i < argc; i++) { | |
numbers[i] = atoi(argv[i]); | |
} | |
mergesort (numbers, argc); | |
for (i = 0; i < count; i++) { | |
printf("%d ", intv[i]); | |
} | |
printf ("\n"); | |
return 0; | |
} |
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