(* consonantvowel.pas - Determine how many strings of letters
 * contain a desired number of consonants and vowels.
 * But this time, insist that all the letters be different.
 * For example, for 2 consonants and 1 vowel --> 6300 strings
 *                  3 consonants and 2 vowels --> 1,596,000 strings
 *)
program consonantvowel2;

const
  desiredConsonants = 3;
  desiredVowels = 2;

var
  firstString, lastString, s : string;
  numVowels, i : integer;
  count : int32;

(*******************************************************************)
function isVowel(c : char) : boolean;
  var
    result : boolean;
    
  begin
    if (c = 'a') or (c = 'e') or (c = 'i') or (c = 'o') or (c = 'u') then
      result := true
    else
      result := false;
      
    isVowel := result;
  end;

(*******************************************************************)
function countVowels(s : string) : integer;
  var
    i, count : integer;
  
  begin
    count := 0;
    for i := 1 to length(s) do
      if isVowel(s[i]) then
        count := count + 1;
        
    countVowels := count;
  end;

(*******************************************************************)
function nextString(s : string) : string;
  var
    i : integer;
    done : boolean;
  
  begin
    i := desiredConsonants + desiredVowels;
    done := false;
    while not done do
      begin
        (* As long as the letter is not z, go to next letter. *)
        if s[i] <> 'z' then
          begin
            s[i] := chr(ord(s[i]) + 1);
            done := true;
          end
        (* In case of z, back up a letter and try incrementing it. *)
        else
          s[i] := 'a';
          i := i - 1;
          if i = 0 then
            done := true;
      end;

    nextString := s;
  end;

(*******************************************************************)
function anyDuplication(s : string) : boolean;
  var
    i, j : integer;
    foundDuplicate : boolean;
    
  begin
    foundDuplicate := false;
    
    for i := 1 to length(s) - 1 do
      for j := i+1 to length(s) do
        if s[i] = s[j] then
          foundDuplicate := true;
    
    anyDuplication := foundDuplicate;
  end;

(*******************************************************************)
(* MAIN PROGRM *)
begin
  (* Start the string at 'aaaaa'.  Cycle through each possible string one at
   * a time like an odometer, until we reach 'zzzzz'.
   *)
  firstString := '';
  lastString := '';
  for i := 1 to desiredConsonants + desiredVowels do
    begin
      firstString := firstString + 'a';
      lastString := lastString + 'z';
    end;

  s := firstString;
  count := 0;
  
  repeat
    numVowels := countVowels(s);
    if (numVowels = desiredVowels) and (anyDuplication(s) = false) then
      begin
        writeln(s);
        count := count + 1;
      end;  
    s := nextString(s);
  until s = lastString;

  writeln('I found ', count, ' strings with ', desiredConsonants,
          ' consonants and ', desiredVowels, ' vowels.');
end.