Practice Web Page - http://www.cs.tau.ac.il/~efif/courses/Software1_Summer_03
int rand() - returns a pseudo-random integer between
0 and RAND_MAX
srand(unsigned int seed) - sets seed
as the seed for a new sequence of pseudo-random integers to be returned by
rand(). These sequences are repeatable by calling srand() with
the same seed value.
/*
* The behavior of rolling a pair of dice.
*
* The total roll can be anywhere from 2 to. We want to count how often each
* roll comes up. We use an array to keep track of the counts: a[2] will count
* how many times we've rolled 2, etc.
*
* We simulate the roll of a die by calling C's random number generation
* function, rand(). Each time rand() is called, it returns a different,
* pseudo-random integer. The values that rand() returns typically span a large
* range. We use C's modulus (or ``remainder'') operator % to produce random
* numbers in the range we want. The expression rand() % 6 produces random
* numbers in the range 0 to 5, and rand() % 6 + 1 produces random numbers in
* the range 1 to 6.
*/
#include <stdio.h>
#include <stdlib.h>
main ()
{
int i;
int d1, d2;
int a[13]; /* uses [2..12] */
/* Initialize: */
for (i = 2; i <= 12; i++)
a[i] = 0;
/* Compute: */
for (i = 0; i < 1000; i++) {
d1 = rand() % 6 + 1;
d2 = rand() % 6 + 1;
a[d1 + d2] = a[d1 + d2] + 1;
}
/* Print out: */
for (i = 2; i <= 12; i++)
printf ("%2d: %3d\n", i, a[i]);
return 0;
}
|
void swap(int i, int j)
{
int temp;
temp = buffer[i];
buffer[i] = buffer[j];
buffer[j] = temp;
}
|
#include <stdio.h>
#include <stdlib.h>
#define BUFFER_SIZE 100
int buffer[BUFFER_SIZE];
int main()
{
int i, j, current;
/* reading input */
for (i = 0; i < BUFFER_SIZE && (scanf("%d", ¤t) == 1); ++i)
buffer[i] = current;
if (i >= BUFFER_SIZE)
return -1;
insertion_sort(i);
/* quick_sort(0, i-1); */
/* printing the sorted array */
for (j = 0; j < i; ++j)
printf("%d ", buffer[j]);
printf("\n");
return 0;
}
|
void insertion_sort(int size)
{
int j, k;
for (j = 1; j < size; ++j)
for (k = j; k > 0 && (buffer[k] < buffer[k-1]); --k)
swap(k, k-1);
}
|
void quick_sort(int left, int right)
{
int i, last;
if (left >= right)
return;
swap(left, (left + right) / 2);
last = left;
for (i = left + 1; i <= right; ++i)
if (buffer[i] < buffer[left])
swap(++last, i);
swap(left, last);
quick_sort(left, last - 1);
quick_sort(last + 1, right);
}
|
int getopt(int argc, char * const argv[], const char *optstring); |
char * optarg = NULL; int opterr = 1; int optind = 1; int optopt = 0; |
static void print_help(char * progName)
{
printf("Usage: %s [options]\n\
-h \t\t\tprint this help message\n\
-i |
