Day 01

• Problem description

This problem relates to positions of a dial and left/right rotations.

Tips

-textread works well, but results in a cell array of strings. You can replace part of a string with another (e.g. think about what ‘R’ could become)

• don’t forget to convert strings to numbers with str2double() (still a cell array after conversion?)
• think about how R and L rotations affect the position of the dial (adding and subtracting to the dial position)
• 99 is the highest possible position and 0 the lowest, so things happen mod(x, 100). Look up modular arithmetic if you are not familiar with it.

• remember the starting point of the dial (not 0)

• cumsum looks like it might be your friend, but a loop and logical checks might be a better idea

Second problem

Rather than keeping track of all end points after the rotations, you need to keep track of all the positions visited on the way.

%% idea for part 2 is:
% keep track of all the dial position visited, so
% R50 = +50 becomes a segment 0 + 1:50... careful to keep MOD!
% so +5000 would be 0 + mod(1:5000, 100)

• negative rotations need a differnt range (or switch to rem from mod?)

Matlab solution (no peeking!)

Matlab code / solution for the first part of that problem.

Second part solution of that problem.