ransom.c

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

int *add_counts(char *corpus, int *counts) {
  int i = 0;
  while (corpus[i]) {
    counts[corpus[i]]++;
    i++;
  }
  return counts;
}

int check_message(char *corpus, char *message) {
  int corpus_freq[256];
  int message_freq[256];

  add_counts(corpus, corpus_freq);

  int i = 0;
  while (message[i]) {
    char c = message[i];
    int f  = ++message_freq[c];

    if (f > corpus_freq[c]) {
      return -1;
    }
    
    i++;
  }

  return 0;
}

int main() {
  static char note[]   = "Give me money, or else...";
  static char magazine[] = "The Weinstein Company pulled their Grace Kelly biopic Grace of Monaco from the release calendar Thursday. It’s the third release change in the past six months. Directed by Olivier Dahan and starring Nicole Kidman as the late princess, the film was originally set for a Nov. 27, 2013, release.";

  if (check_message(magazine, note) < 0) {
    printf("Source cannot be used to write note\n");
    return -1;
  }
  else {
    printf("Source can be used to write note\n");
    return 0;
  }
}