university/S1/GdCP/klausur_uebung/brueche.c

#include<stdlib.h>
#include<stdio.h>
#include<time.h>

// This is the definition for a fraction from the task
typedef struct {
  int n;
  int d;
} fraction_t;

fraction_t sub_frac(fraction_t *a, fraction_t *b) {
  // this function should substract fractions from anonther
  // with the condition that a/b - c/d = (ad + bc)/(bd)
  // also check that the negative sign always is on the nominator

  fraction_t r = {0};

  // Check for edge cases
  if (!a || !b || a->d == 0 || b->d == 0) return r;


  // Calculate the result
  r.n = a->n * b->d - a->d * b->n;
  r.d = a->d * b->d;

  // flip the signs
  if (r.d < 0) {
    r.d *= -1; r.n *= -1;
  }
  
  return r;
}

fraction_t *max_frac(fraction_t a[], int l) {
  // This function should return a pointer to the biggest fraction in the array
  // Do this with the condition that if a - b < 0 it follows that a < b.

  // Init the max
  fraction_t *m = a;

  // Find the max
  for (int i = 1; i < l; i++) {
    if (sub_frac(m, a + i).n < 0) {
      m = a + i;
    }
  }

  return m;
}

#define N 10

void print_frac(fraction_t *f) {
  printf("%d/%d ", f->n, f->d);
}

int main() {
  // Seed the randomness
  srand(time(NULL));

  // Generate a list of random fractions
  fraction_t l[N];
  for (int i = 0; i < N; i++) {
    fraction_t r = {rand()%5+1, rand()%5+1};

    // Also give a random sign
    if (rand()%2 == 0) {
      r.n *= -1;
    }
    l[i] = r;
  }

  // print the fracions
  for (int i = 0; i < N; i++) {
    print_frac(l +i);
  }
  putchar('\n');

  // Print the max Fraction
  fraction_t *max = max_frac(l, N);
  printf("The max fraction is: ");
  print_frac(max);
  putchar('\n');
}