UVa 346 - Getting Chorded

Accepted date: 2014-12-27
Ranking (as of 2014-12-27): 33 out of 406
Language: C++

/*
  UVa 346 - Getting Chorded

  To build using Visual Studio 2012:
    cl -EHsc -O2 UVa_346_Getting_Chorded.cpp
*/

#include <cstdio>
#include <cstring>
#include <cctype>

#ifdef ONLINE_JUDGE
#define _stricmp strcasecmp
#endif

const int nr_chars_max = 3, nr_notes = 3, index_max = 12;

struct note {
  char s_[nr_chars_max + 1];
  int ci_, i_;
};

const note chromatic_notes[] = {
  {"A", 0}, {"A#", 1}, {"Bb", 1}, {"B", 2}, {"Cb", 2}, {"B#", 3},
  {"C", 3},{"C#", 4}, {"Db", 4}, {"D", 5}, {"D#", 6},
  {"Eb", 6}, {"E", 7}, {"Fb", 7}, {"E#", 8}, {"F", 8}, {"F#", 9},
  {"Gb", 9}, {"G", 10}, {"G#", 11}, {"Ab", 11}
};

void get_index(note& n)
{
  int i;
  for (i = 0; i < sizeof(chromatic_notes) / sizeof(note); i++)
    if (!_stricmp(n.s_, chromatic_notes[i].s_))
      break;
  n.ci_ = chromatic_notes[i].ci_; n.i_ = i;
}

const char* get_key(const note& n)
{
  int i = n.i_;
  if (n.s_[1] == 'b')
    i--;
  else if (n.s_[1] == '#') {
    if (chromatic_notes[i].s_[0] == 'B' || chromatic_notes[i].s_[0] == 'E')
      i++;
  }
  return chromatic_notes[i].s_;
}

int main()
{
  const int perms[][nr_notes] = {
    {0, 1, 2}, {0, 2, 1}, {1, 0, 2}, {1, 2, 0}, {2, 0, 1}, {2, 1, 0}
  };

  note notes[nr_notes];
  while (scanf("%s %s %s", notes[0].s_, notes[1].s_, notes[2].s_) != EOF) {
    for (int i = 0; i < nr_notes; i++)
      get_index(notes[i]);
    bool recognized = false;
    for (size_t i = 0; i < sizeof(perms) / sizeof(perms[0]); i++) {
      int third = notes[perms[i][1]].ci_ - notes[perms[i][0]].ci_,
        fifth = notes[perms[i][2]].ci_ - notes[perms[i][0]].ci_;
      char key[nr_chars_max + 1];
      if (third < 0)
        third += index_max;
      if (fifth < 0)
        fifth += index_max;
      if (third == 4 && fifth == 7) {
        recognized = true;
        printf("%s %s %s is a %s Major chord.\n",
          notes[0].s_, notes[1].s_, notes[2].s_, get_key(notes[perms[i][0]]));
        break;
      }
      else if (third == 3 && fifth == 7) {
        recognized = true;
        printf("%s %s %s is a %s Minor chord.\n",
          notes[0].s_, notes[1].s_, notes[2].s_, get_key(notes[perms[i][0]]));
        break;
      }
    }
    if (!recognized)
      printf("%s %s %s is unrecognized.\n", notes[0].s_, notes[1].s_, notes[2].s_);
  }
  return 0;
}