Computer Science 15-110, Spring 2011
Class Notes:  2d Lists Practice (Problem-Solving)

1. More coming soon....
   
2. Word Search
3. Sample Solutions
   

1. More coming soon...
   More examples are coming soon...
   
   
2. Word Search
   Write the function wordSearch that takes two parameters, a puzzle (a 2d list of characters) and a word, and if the word is in the puzzle, the function returns a tuple (see comment below) of the starting location and the direction of the word, otherwise the function returns None (meaning the word is not in the puzzle).   Here is a sample puzzle:
        puzzle = [ [ 'a', 'q', 'r', 'z' ],
                   [ 'g', 'o', 'd', 'q' ],
                   [ 'w', 'm', 'z', 'c' ]
                 ]
   And here is a smple call to the wordSearch function:
        print wordSearch(puzzle, "dog")
   Notice that the word "dog" occurs in row 1 (the second row), starting at column 2 (the third column), heading to the left.  To represent directions (headings), we will use a tuple of two numbers -- (drow, dcol) -- representing the change in row and change in col necessary to take one step in that direction.  Thus, "left" is represented as (0, -1), since to take one step left we do not change our row but we subtract one from our column. Thus, the example above prints:
        (1,2,(0,-1))
   This means the word "dog" was found, starting at row 1 and col 2, and heading left (0, -1).
   
   Note:  What is a tuple?  A tuple is just like a list, only it is created using parentheses instead of brackets.  So [2,3] is a list, but (2,3) is a tuple. Unlike lists, tuples are immutable (unchangeable).  So, if a = (2,3), then you cannot say a[0] = 4, because you cannot change values in the tuple.  Tuples are more efficient than lists, and so they are often used when returning multiple values from a function.
   
   
3. Sample Solutions
1. Word Search
   

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