// With the toboggan login problems resolved, you set off toward the airport. While travel by toboggan might be easy, it's certainly not safe: there's very minimal steering and the area is covered in trees. You'll need to see which angles will take you near the fewest trees.
// Due to the local geology, trees in this area only grow on exact integer coordinates in a grid. You make a map (your puzzle input) of the open squares (.) and trees (#) you can see. For example:
// ..##.......
// #...#...#..
// .#....#..#.
// ..#.#...#.#
// .#...##..#.
// ..#.##.....
// .#.#.#....#
// .#........#
// #.##...#...
// #...##....#
// .#..#...#.#
// These aren't the only trees, though; due to something you read about once involving arboreal genetics and biome stability, the same pattern repeats to the right many times:
// You start on the open square (.) in the top-left corner and need to reach the bottom (below the bottom-most row on your map).
// The toboggan can only follow a few specific slopes (you opted for a cheaper model that prefers rational numbers); start by counting all the trees you would encounter for the slope right 3, down 1:
// From your starting position at the top-left, check the position that is right 3 and down 1. Then, check the position that is right 3 and down 1 from there, and so on until you go past the bottom of the map.
// The locations you'd check in the above example are marked here with O where there was an open square and X where there was a tree:
// In this example, traversing the map using this slope would cause you to encounter 7 trees.
// Starting at the top-left corner of your map and following a slope of right 3 and down 1, how many trees would you encounter?
funcmain(){
file,_:=os.Open("input.txt")
deferfile.Close()
@ -44,6 +98,20 @@ func main() {
// Part 2
// Time to check the rest of the slopes - you need to minimize the probability of a sudden arboreal stop, after all.
// Determine the number of trees you would encounter if, for each of the following slopes, you start at the top-left corner and traverse the map all the way to the bottom:
// Right 1, down 1.
// Right 3, down 1. (This is the slope you already checked.)
// Right 5, down 1.
// Right 7, down 1.
// Right 1, down 2.
// In the above example, these slopes would find 2, 7, 3, 4, and 2 tree(s) respectively; multiplied together, these produce the answer 336.
// What do you get if you multiply together the number of trees encountered on each of the listed slopes?
// You arrive at the airport only to realize that you grabbed your North Pole Credentials instead of your passport. While these documents are extremely similar, North Pole Credentials aren't issued by a country and therefore aren't actually valid documentation for travel in most of the world.
// It seems like you're not the only one having problems, though; a very long line has formed for the automatic passport scanners, and the delay could upset your travel itinerary.
// Due to some questionable network security, you realize you might be able to solve both of these problems at the same time.
// The automatic passport scanners are slow because they're having trouble detecting which passports have all required fields. The expected fields are as follows:
// byr (Birth Year)
// iyr (Issue Year)
// eyr (Expiration Year)
// hgt (Height)
// hcl (Hair Color)
// ecl (Eye Color)
// pid (Passport ID)
// cid (Country ID)
// Passport data is validated in batch files (your puzzle input). Each passport is represented as a sequence of key:value pairs separated by spaces or newlines. Passports are separated by blank lines.
// Here is an example batch file containing four passports:
// The first passport is valid - all eight fields are present. The second passport is invalid - it is missing hgt (the Height field).
// The third passport is interesting; the only missing field is cid, so it looks like data from North Pole Credentials, not a passport at all! Surely, nobody would mind if you made the system temporarily ignore missing cid fields. Treat this "passport" as valid.
// The fourth passport is missing two fields, cid and byr. Missing cid is fine, but missing any other field is not, so this passport is invalid.
// According to the above rules, your improved system would report 2 valid passports.
// Count the number of valid passports - those that have all required fields. Treat cid as optional. In your batch file, how many passports are valid?
funcmain(){
file,_:=os.Open("input.txt")
deferfile.Close()
@ -49,6 +94,74 @@ ppLoop:
// Part 2, stricter rules
// The line is moving more quickly now, but you overhear airport security talking about how passports with invalid data are getting through. Better add some data validation, quick!
// You can continue to ignore the cid field, but each other field has strict rules about what values are valid for automatic validation:
// byr (Birth Year) - four digits; at least 1920 and at most 2002.
// iyr (Issue Year) - four digits; at least 2010 and at most 2020.
// eyr (Expiration Year) - four digits; at least 2020 and at most 2030.
// hgt (Height) - a number followed by either cm or in:
// If cm, the number must be at least 150 and at most 193.
// If in, the number must be at least 59 and at most 76.
// hcl (Hair Color) - a # followed by exactly six characters 0-9 or a-f.
// ecl (Eye Color) - exactly one of: amb blu brn gry grn hzl oth.
// pid (Passport ID) - a nine-digit number, including leading zeroes.
// cid (Country ID) - ignored, missing or not.
// Your job is to count the passports where all required fields are both present and valid according to the above rules. Here are some example values:
// Count the number of valid passports - those that have all required fields and valid values. Continue to treat cid as optional. In your batch file, how many passports are valid?
