Advent of Code 2015 Day 6

Solve the Advent Of Code 2015 Day 6 puzzle.

Hints

• You can use a 1000 x 1000 matrix to represent the grid of lights.

• Here is some MATLAB code that you can use to load in the input file. In your MATLAB script, assume the input file is named AOC2015Day6_input.txt), and process each line of the file, first splitting the instructions into a list of items:

  fid = fopen('AOC2015Day6_input.txt');
  tline = fgetl(fid);
  while ischar(tline)
      l = strsplit(tline, ' ');
      % now process the line based on what the instruction is
      % <insert your code here>
      % ...
      tline = fgetl(fid);
  end
  fclose(fid);

  The other way of loading the file is to load it all at once, into a cell array of strings (one string for each line in the file), using the importdata() function:

  I = importdata('AOC2015Day6_input.txt', '%s');

• You will need some if-statements to detemine which instruction it is, and how to act on it.

• You can use the strcmp() function in MATLAB to compare two strings (type help strcmp at the MATLAB command line to see how it works).

• You can use the ~ operator to toggle between 1 and 0. ~0 becomes 1 and ~1 becomes 0.

• Don’t forget that in MATLAB array indexing starts at 1 not at 0.

• You can perform operations on a whole sub-range of a matrix at once. For example to add 1 to a 1000x1000 matrix L from (x1,y1) = (3,4) to (x2,y2) = (10,11) you would write:

  L(3:10,4:11) = L(3:10,4:11) + 1;