Finds whether or not it is possible to find three elements from three arrays such that they sum up to a given value

sum.c

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

int a[MAX], b[MAX], c[MAX], n;

int cmp (const void *a, const void *b) {
  return *((int*) a) - *((int*) b);
}

void read (int v[MAX]) {
  int i;

  for (i = 0; i < n; i++)
    scanf("%d", &v[i]);

  qsort(v, n, sizeof(int), cmp);
}

int find_in_two (int i, int j, int k) {
  if (i >= j)
    return 0;

  int sum = a[i] + b[j];

  if (sum == k)
    return 1;

  if (sum < k)
    return find_in_two(i + 1, j, k);

  return find_in_two(i, j - 1, k);
}

int find (int k, int i) {
  if (i == n)
    return 0;

  if (find_in_two(0, n - 1, k - c[i]))
    return 1;

  return find(k, i + 1);
}

int main () {
  int k;

  while (scanf("%d", &n) != EOF && n != 0) {
    scanf("%d", &k);

    read(a);
    read(b);
    read(c);

    printf("%c\n", find(k, 0) ? 'S' : 'N');
  }

  return 0;
}