find closest points

#include <float.h>
#include <stdio.h>
#include <stdlib.h>
#include <tgmath.h>
static void data_read(int *n, double complex **p) {
  FILE *in = fopen("data.txt", "r");
  if (fscanf(in, "%d", n) != 1) {
    exit(1);
  }
  *p = calloc(sizeof(**p), *n);
  for (int i = 0; i < *n; ++i) {
    double x, y;
    if (fscanf(in, "%lf%lf", &x, &y) != 2) {
      exit(1);
    }
    (*p)[i] = CMPLX(x, y);
  }
  fclose(in);
}
static void find_closest_points(int n, double complex *p, int *index,
                                double *min) {
  *min = DBL_MAX;
  for (int i = 0; i < n; ++i) {
    for (int j = i + 1; j < n; ++j) {
      double dist = fabs(p[i] - p[j]);
      if (dist < *min) {
        *min = dist;
        index[0] = i;
        index[1] = j;
      }
    }
  }
}
static void report(int *index, double min) {
  printf("%d %d %f\n", index[0], index[1], min);
}
int main(void) {
  int n;
  double complex *p;
  data_read(&n, &p);
  {
    int index[2];
    double min;
    find_closest_points(n, p, index, &min);
    report(index, min);
  }
  free(p);
}