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Searching for Bobby Fisher

Special thanks to puzzle regular Roddy Pratt for suggesting the idea for this week's puzzle.

Roddy (*Names may have been changed to protect the innocent) had code similar to the following:







    

  1. 

    function FindBobbyFisher: Integer;
    

    2. 

  2. 

    var
    

    3. 

  3. 

      Names: TStringList;
    

    4. 

  4. 

      I: Integer;
    

    5. 

  5. 

    begin
    

    6. 

  6. 

      Names := TStringList.Create;
    

    7. 

  7. 

      Names.LoadFromFile('names.txt');
    

    8. 

  8. 

      if not Names.Find('Bobby Fisher', I) then
    

    9. 

  9. 

        Result := -1
    

    10. 

  10. 

      else
    

    11. 

  11. 

        Result := I;
    

    12. 

  12. 

      Names.Free;  
    

    13. 

  13. 

    end; 
    

    14.

Roddy's code worked at first, but soon Bobby Fisher could not be found. What is Roddy missing?

This was written by Jacob. Posted on Monday, April 14, 2008, at 1:00 am. Filed under Puzzles. Bookmark the permalink. Follow comments here with the RSS feed. Post a comment or leave a trackback.

2 Comments

  1. Rcus wrote:

    Find method of TStringList works only for sorted lists (cause of binary search algorythm that has O(log(N)) complexity), in case of unsorted lists its result isn’t defined. By default TStringList isn’t sorted but you can do it by calling Sort method (underlying algorythm of quicksort has O(N*log(N))) complexity). If you don’t need to search many times IndexOf method will be faster (N complexity but works for any lists).

    Monday, April 14, 2008 at 2:29 am | Permalink
  2. Jason Sweby wrote:

    Yes the Delphi help says:

    Find will only work on sorted lists!

    Therefore Names.Sort; should be added after the LoadFromFile call.

    Monday, April 14, 2008 at 8:31 am | Permalink

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