Scrabble Word Placement C#

I'm currently writing a scrabble-like game in C#. I can get the computer to find the highest point开发者_Go百科 value word that can be made using the current rack, however I have no idea how to check if that word is "Placeable" on the 15*15 Gameboard(2D Array: string[,]).

In it's default state(with no Letters on the board) all elements are set to 0.

Is allowed

---------------
-------H-------
-------E-------
-----FILL------
-------L-------
-------O-------
---------------

How can I check if the word is not For example:

Is Not Allowed

 ---------------
 -H-------------
 -E-------------
FILL------------ <-- F is out of bounds
 -L-------------
 -O-------------
 ---------------

Is Not Allowed

 ---------------
 -H-------------
 -E-W-----------
 -L-O-----------
 -L-R-----------
 FOLL----------- <-- Fill is overlapping with O
 ---D-----------

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The paper, "The worlds fastest Scrabble engine" (PDF), is from 1988 and describes an efficient Scrabble engine. It's short and surprisingly readable!

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I learned how to do this based on the F# SharpScrabble project. Even if you don't know F# (like me), you'll get a feel for how the author decided to do this.

The big things to me were:

• Using a Coordinate system to find Tiles
• Populating the Board with Squares that can hold a tile (letter) but also hold score information
• Tile represents a letter, both in the player's letter bank and also on the board
• Move that represents a player's placement of letters
• Implementing the IComparable on coordinates and tiles to make sorting easier
• Computing Runs which represent the words a move would place, to compute score

Overall, a really good primer on beginning to wrap your head around a Scrabble engine. I was able to port much of that code into C# without knowing F# a lick, so it shouldn't be terrible for anyone else.