C-Code

/*****************************************
 * random_feather.c  Zufallsweg der Feder
 *****************************************/
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <limits.h>

#define MAX_TRIALS      UINT_MAX

#define BORDER_A        0   // +-------+  +---->x
#define BORDER_B       10   // |       |  |
#define START_X         0   // |       |  |
#define START_Y         0   // |       |  V
#define LENGTH         50   // |       |  y


/* random seed generator */
int init_random_seed(void) {
  return open("/dev/urandom", O_RDONLY);
}

void get_random_seed(int urandom_fd, unsigned int *seed) {
  if (urandom_fd > 0) {
    /* get seed from the urandom device */
    read(urandom_fd, seed, sizeof(unsigned int));
  }
}

/* main */
int main(int argc, char **argv) {
    unsigned int total, total_left, total_right, total_succ;
    unsigned int t, tmax, seed_val;
    int direction, seed_rc;
    int x_start, x, y;

    tmax = MAX_TRIALS;
    if (argc > 1)
        tmax = (unsigned)atoi(argv[1]);

	printf("Streckenlänge  : %u\n", LENGTH);
    printf("Anzahl Versuche: %u\n", tmax);

    seed_rc = init_random_seed();
    if (seed_rc <= 0) {
		fprintf(stderr, "cannot seed random number generator\n");
		exit(EXIT_FAILURE);
	}

	for (x_start=START_X; x_start<=BORDER_B; x_start++) {
		total_left=total_right=total_succ=total=0;
		get_random_seed(seed_rc, &seed_val);

		for (t=1; t<=tmax; t++, total++) {
			get_random_seed(seed_rc, &seed_val);
			srand(seed_val);

			x = x_start;
			y = START_Y;
			for (;;) {
				direction = (int)(2L*rand()/RAND_MAX);
				switch (direction) {
					case 0:	--x; ++y; break;
					case 1:	++x; ++y; break;
				   default: continue;
				}
				if (x < BORDER_A) {
					total_left++;
					break;
				}
				else if (x > BORDER_B) {
					total_right++;
					break;
				}
				else if (y > LENGTH) {
					total_succ++;
					break;
				}
			}
		}
		printf("|----------------------------|\n");
		printf("Startposition : a=%u, b=%u\n", x_start, BORDER_B-x_start);
		printf("Risiko links  : %4.1f%%\n", 100.0*total_left/total);
		printf("Risiko rechts : %4.1f%%\n", 100.0*total_right/total);
		printf("Erfolgschance : %4.1f%%\n", 100.0*total_succ/total);
	}
    return 0;
}