Program to solve the daily programmer challenge #200 by Joseph Halstead. The specifics of the puzzle can be found at: http://www.reddit.com/r/dailyprogrammer/comments/2uo3yf/20150204_challenge_200_intermediate_metro_tile/ Program flows as follows: 1) Import the puzzle data from a file 2) Loop through each character in the grid and check whether it is the beginning of a rectangle. If it is then get the dimensions of the rectangle and mark each character within the rectangle as visited. 3) Repeat until at the end of the grid.