pub fn parse(input: &str) -> (usize, Vec<i8>)Expand description
Convert a 2D grid of ASCII digits into a 1D vec of heights.
Each height is multipled by 6. For part 1 this makes no difference, but for part 2 this helps with the bit manipulation.
To convert from 2D co-ordinates to an index, the formula is y * width + x. For the sample grid
of width 5, the top middle point at (2, 0) is at index 0 * 5 + 2 = 2 and the point directly
below (2, 1) is at index 1 * 5 + 2 = 7.
Using a 1D vec instead of a vec of vecs is faster for 2 reasons:
- Avoids an intermediate pointer lookup for each access.
- Better cache locality as the memory locations are adjacent and not potentially scattered all over the heap.