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#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#define N 1000
#if N > 1000000
#error "Value of N too big, must be <= 1000000"
#endif
#define LOG10_N 6
#define N_FORMAT "%06d"
#if N <= 1000
static void insert_sort(char *strings[], int n)
{
char *v, *t;
char **strp, **endp;
int i;
endp = &strings[N-1];
i = N-2;
do {
strp = &strings[i];
v = strp[0];
do {
t = strp[1];
if (strcmp(v, t) <= 0) break;
*strp++ = t;
} while (strp < endp);
strp[0] = v;
} while (--i >= 0);
}
#endif
static void shell_sort(char *strings[], int n)
{
int h, i, j;
char *v;
strings--; /* Make array 1 origin */
h = 1;
do {h = h * 3 + 1;} while (h <= n);
do {
h = h / 3;
for (i = h + 1; i <= n; i++) {
v = strings[i];
j = i;
while (j > h && strcmp(strings[j-h], v) > 0) {
strings[j] = strings[j-h];
j = j-h;
}
strings[j] = v;
}
}
while (h > 1);
}
static void randomise(char *strings[], int n)
{
int i;
int v;
char *t;
/* srand(clock()); /* comment out for reproducible results */
for (i = 0; i < N; i++) {
v = rand() % N;
t = strings[v];
strings[v] = strings[i];
strings[i] = t;
}
}
static void check_order(char *sort_type, char *strings[], int n)
{
int i;
for (i = 0; i < n; i++) {
if (atoi(strings[i]) != i) {
fprintf(stderr, "%s sort failed - exiting\n", sort_type);
exit(1);
}
}
}
int qs_string_compare(const void *a, const void *b)
{
return strcmp(*(char **)a, *(char **)b);
}
int main(void)
{
char *strings[N], *strings_copy[N];
char buffer[N*(LOG10_N+1)];
char *p;
clock_t starttime, endtime;
int i;
p = buffer;
for (i = 0; i < N; i++) {
sprintf(p, N_FORMAT, i);
strings[i] = p;
p += LOG10_N+1;
}
randomise(strings, N);
#if N <= 1000
/* Do insertion sort */
memcpy(strings_copy, strings, sizeof(strings));
starttime = clock();
insert_sort(strings_copy, N);
endtime = clock();
check_order("Insertion", strings_copy, N);
printf("Insertion sort took %d clock ticks\n", endtime - starttime);
#else
printf("Value of N too big to use insertion sort, must be <= 1000\n");
#endif
/* Do shell sort */
memcpy(strings_copy, strings, sizeof(strings));
starttime = clock();
shell_sort(strings_copy, N);
endtime = clock();
check_order("Shell", strings_copy, N);
printf("Shell sort took %d clock ticks\n", endtime - starttime);
/* Do quick sort - use built-in C library sort */
memcpy(strings_copy, strings, sizeof(strings));
starttime = clock();
qsort(strings_copy, N, sizeof(char *), qs_string_compare);
endtime = clock();
check_order("Quick", strings_copy, N);
printf("Quick sort took %d clock ticks\n", endtime - starttime);
}
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