I hardly found anything useful, but i did find this piece of code which i am not really understanding well...
Code:
/*
* This program checks the length of a tour. Give the points data file
* name on the command line.
*/
#include <stdio.h>
#include <math.h>
typedef struct _point {
float x, y, z;
} point;
float distance (point v[], int i, int j) {
float dx, dy, dz;
dx = v[i].x - v[j].x;
dy = v[i].y - v[j].y;
dz = v[i].z - v[j].z;
return sqrt (dx*dx + dy*dy + dz*dz);
}
float tour_length (int tour[], point v[], int n) {
int i, from, to;
float sum;
/* sum up distances between cities on the tour */
sum = 0;
/* start at city 0 */
from = 0;
for (i=1; i<n; i++) {
/* find distance to next city in tour */
to = tour[i];
/* add that to the length of the tour */
sum += distance (v, from, to);
/* the next source is the current target */
from = to;
}
/* add in the distance back to the first city */
sum += distance (v, from, 0);
return sum;
}
int main (int argc, char *argv[]) {
char present[1000];
int i, j, n, tour[1000];
float length, min;
point cities[1000];
FILE *f;
if (argc != 2) {
fprintf (stderr, "Usage: %s <filename>\n", argv[0]);
exit (1);
}
f = fopen (argv[1], "r");
if (!f) {
perror (argv[1]);
exit (1);
}
fscanf (f, "%d\n", &n);
for (i=0; i<n; i++) {
fscanf (f, "%f %f %f\n", &cities[i].x, &cities[i].y, &cities
[i].z);
}
fclose (f);
bzero (present, n);
for (i=0; i<n; i++) {
scanf ("%i", &tour[i]);
if (feof (stdin)) {
fprintf (stderr, "unexpected end of file!\n");
exit (1);
}
if (tour[i] >= 0 && tour[i] < n)
present[i] = 1;
else {
fprintf (stderr, "index %d out of bounds!\n", tour
[i]);
exit (1);
}
}
for (i=0; i<n; i++) if (!present[i]) {
fprintf (stderr, "not all points in tour, missing %d!\n",
i);
exit (1);
}
length = tour_length (tour, cities, n);
printf ("length of tour is %f\n", length);
exit (0);
}
Can anyone explian it to me?/
