pub fn y15d09(input: &str, part: u32) -> u32Expand description
The solution for the day nine challenge.
We take the input as a string and the problem part as an integer as usual.
We start by iterating over the lines and parsing the city names and the
distances. We maintain a std::collections::HashMap of the city names
with their values equal to another HashMap that contains the other cities
and their distances. This way we can lookup the distance from one city to
any other city. Then we get all of the permutations of the cities which
gives us all of the possible trips that we could take and then look at them
by two to give us each leg of the trip. Just get the distance for the trip
and then add it to the std::collections::BinaryHeaps that we’ve been
maintaining of the trip distances. If we’re on part one then get the value
from the min-heap, otherwise the value from the max-heap.
§Example
// probably read this from the input file...
let input = "A to B = 10\nB to C = 15\nA to C = 25\n";
assert_eq!(y15d09(input, 1), 25);
assert_eq!(y15d09(input, 2), 40);