use std::collections::HashMap;
-fn parse_quantity_and_name(input: &str) -> (i32, String) {
- let quantity_and_name: Vec<&str> = input.split(" ").collect();
- (
- quantity_and_name[0].parse::<i32>().unwrap(),
- String::from(quantity_and_name[1].trim())
- )
+#[derive(Debug)]
+pub struct Chemical {
+ quantity: i64,
+ name: String,
}
-fn parse(input: &str) -> HashMap<String, (i32, Vec<(i32, String)>)> {
- let result = HashMap::<String, (i32, Vec<(i32, String)>)>::new();
+type Reactions = HashMap<String, (i64, Vec<Chemical>)>;
+
+fn parse_chemical(input: &str) -> Chemical {
+ let quantity_and_name: Vec<&str> = input.trim().split(' ').collect();
+ Chemical {
+ quantity: quantity_and_name[0].parse::<i64>().unwrap(),
+ name: String::from(quantity_and_name[1].trim()),
+ }
+}
+
+pub fn parse(input: &str) -> Reactions {
+ let mut result = Reactions::new();
for line in input.lines() {
let reaction: Vec<&str> = line.split("=>").collect();
- let input_chemicals: Vec<(i32, String)> =
- reaction[0].split(",").map(parse_quantity_and_name).collect();
+ let input_chemicals: Vec<Chemical> = reaction[0].split(',').map(parse_chemical).collect();
+ let output_chemical = parse_chemical(reaction[1]);
+ result.insert(output_chemical.name, (output_chemical.quantity, input_chemicals));
}
result
}
+pub fn ore_needed_per_fuel(reactions: &Reactions) -> i64 {
+ let mut remainders = HashMap::new();
+ ore_needed(reactions, 1, &mut remainders)
+}
+
+fn ore_needed(reactions: &Reactions, fuel_quantity: i64, remainders: &mut HashMap<String, i64>) -> i64 {
+
+ fn needed(reactions: &Reactions, chemicals: &[Chemical], remainders: &mut HashMap<String, i64>) -> i64 {
+ chemicals.iter().fold(0, |sum, chemical| {
+ let quantity_needed =
+ match remainders.get(&chemical.name) {
+ Some(quantity) => {
+ let remainder = quantity - chemical.quantity;
+ if remainder < 0 {
+ remainders.remove(&chemical.name);
+ remainder.abs()
+ } else {
+ remainders.insert(chemical.name.clone(), remainder);
+ 0
+ }
+ },
+ None => chemical.quantity
+ };
+
+ sum +
+ if chemical.name == "ORE" {
+ quantity_needed
+ } else {
+ match reactions.get(&chemical.name) {
+ Some((quantity_produced, chemicals_needed)) => {
+ let n = (quantity_needed / quantity_produced) + (if quantity_needed % quantity_produced == 0 { 0 } else { 1 });
+ let rem = n * quantity_produced - quantity_needed;
+ match remainders.get(&chemical.name) {
+ Some(&q) => { remainders.insert(chemical.name.clone(), q + rem); },
+ None => { remainders.insert(chemical.name.clone(), rem); }
+ }
+ needed(reactions, &chemicals_needed.iter().map(|c| Chemical { quantity: n * c.quantity, name: c.name.clone() }).collect::<Vec<Chemical>>(), remainders)
+ },
+ None => panic!("Unable to find reaction to create {}", chemical.name)
+ }
+ }
+ })
+ }
+
+ needed(reactions, &[Chemical { quantity: fuel_quantity, name: String::from("FUEL") }], remainders)
+}
+
+pub fn fuel_produced(reactions: &Reactions, ore: i64, ore_per_fuel: i64) -> i64 {
+ let mut ore_available = ore;
+ let mut fuel_produced = 0;
+ let mut remainders = HashMap::new();
+
+ loop {
+ let fuel = 1.max(ore_available / ore_per_fuel); // Approximate the fuel we can produce.
+ ore_available -= ore_needed(reactions, fuel, &mut remainders);
+
+ if ore_available <= 0 {
+ return fuel_produced
+ }
+
+ fuel_produced += fuel;
+ }
+}
+
#[cfg(test)]
mod tests {
use super::*;
#[test]
- fn part1() {
+ fn part1_sample_1() {
+ let input =
+ "10 ORE => 10 A
+ 1 ORE => 1 B
+ 7 A, 1 B => 1 C
+ 7 A, 1 C => 1 D
+ 7 A, 1 D => 1 E
+ 7 A, 1 E => 1 FUEL";
+ let reactions = parse(input);
+ assert_eq!(ore_needed_per_fuel(&reactions), 31);
+ }
+
+ #[test]
+ fn part1_sample_2() {
+ let input =
+ "9 ORE => 2 A
+ 8 ORE => 3 B
+ 7 ORE => 5 C
+ 3 A, 4 B => 1 AB
+ 5 B, 7 C => 1 BC
+ 4 C, 1 A => 1 CA
+ 2 AB, 3 BC, 4 CA => 1 FUEL";
+ let reactions = parse(input);
+ assert_eq!(ore_needed_per_fuel(&reactions), 165);
+ }
+
+ #[test]
+ fn part1_sample_3() {
+ let input =
+ "157 ORE => 5 NZVS
+ 165 ORE => 6 DCFZ
+ 44 XJWVT, 5 KHKGT, 1 QDVJ, 29 NZVS, 9 GPVTF, 48 HKGWZ => 1 FUEL
+ 12 HKGWZ, 1 GPVTF, 8 PSHF => 9 QDVJ
+ 179 ORE => 7 PSHF
+ 177 ORE => 5 HKGWZ
+ 7 DCFZ, 7 PSHF => 2 XJWVT
+ 165 ORE => 2 GPVTF
+ 3 DCFZ, 7 NZVS, 5 HKGWZ, 10 PSHF => 8 KHKGT";
+ let reactions = parse(input);
+ assert_eq!(ore_needed_per_fuel(&reactions), 13_312);
+ }
+ #[test]
+ fn part1_sample_4() {
+ let input =
+ "2 VPVL, 7 FWMGM, 2 CXFTF, 11 MNCFX => 1 STKFG
+ 17 NVRVD, 3 JNWZP => 8 VPVL
+ 53 STKFG, 6 MNCFX, 46 VJHF, 81 HVMC, 68 CXFTF, 25 GNMV => 1 FUEL
+ 22 VJHF, 37 MNCFX => 5 FWMGM
+ 139 ORE => 4 NVRVD
+ 144 ORE => 7 JNWZP
+ 5 MNCFX, 7 RFSQX, 2 FWMGM, 2 VPVL, 19 CXFTF => 3 HVMC
+ 5 VJHF, 7 MNCFX, 9 VPVL, 37 CXFTF => 6 GNMV
+ 145 ORE => 6 MNCFX
+ 1 NVRVD => 8 CXFTF
+ 1 VJHF, 6 MNCFX => 4 RFSQX
+ 176 ORE => 6 VJHF";
+ let reactions = parse(input);
+ assert_eq!(ore_needed_per_fuel(&reactions), 180_697);
+ }
+
+ #[test]
+ fn part1_sample_5() {
+ let input =
+ "171 ORE => 8 CNZTR
+ 7 ZLQW, 3 BMBT, 9 XCVML, 26 XMNCP, 1 WPTQ, 2 MZWV, 1 RJRHP => 4 PLWSL
+ 114 ORE => 4 BHXH
+ 14 VRPVC => 6 BMBT
+ 6 BHXH, 18 KTJDG, 12 WPTQ, 7 PLWSL, 31 FHTLT, 37 ZDVW => 1 FUEL
+ 6 WPTQ, 2 BMBT, 8 ZLQW, 18 KTJDG, 1 XMNCP, 6 MZWV, 1 RJRHP => 6 FHTLT
+ 15 XDBXC, 2 LTCX, 1 VRPVC => 6 ZLQW
+ 13 WPTQ, 10 LTCX, 3 RJRHP, 14 XMNCP, 2 MZWV, 1 ZLQW => 1 ZDVW
+ 5 BMBT => 4 WPTQ
+ 189 ORE => 9 KTJDG
+ 1 MZWV, 17 XDBXC, 3 XCVML => 2 XMNCP
+ 12 VRPVC, 27 CNZTR => 2 XDBXC
+ 15 KTJDG, 12 BHXH => 5 XCVML
+ 3 BHXH, 2 VRPVC => 7 MZWV
+ 121 ORE => 7 VRPVC
+ 7 XCVML => 6 RJRHP
+ 5 BHXH, 4 VRPVC => 5 LTCX";
+ let reactions = parse(input);
+ assert_eq!(ore_needed_per_fuel(&reactions), 2_210_736);
+ }
+
+ #[test]
+ fn part2_sample_1() {
+ let input =
+ "157 ORE => 5 NZVS
+ 165 ORE => 6 DCFZ
+ 44 XJWVT, 5 KHKGT, 1 QDVJ, 29 NZVS, 9 GPVTF, 48 HKGWZ => 1 FUEL
+ 12 HKGWZ, 1 GPVTF, 8 PSHF => 9 QDVJ
+ 179 ORE => 7 PSHF
+ 177 ORE => 5 HKGWZ
+ 7 DCFZ, 7 PSHF => 2 XJWVT
+ 165 ORE => 2 GPVTF
+ 3 DCFZ, 7 NZVS, 5 HKGWZ, 10 PSHF => 8 KHKGT";
+ let reactions = parse(input);
+ let ore_per_fuel = ore_needed_per_fuel(&reactions);
+ assert_eq!(fuel_produced(&reactions, 1_000_000_000_000, ore_per_fuel), 82_892_753);
+ }
+
+ #[test]
+ fn part2_sample_2() {
+ let input =
+ "2 VPVL, 7 FWMGM, 2 CXFTF, 11 MNCFX => 1 STKFG
+ 17 NVRVD, 3 JNWZP => 8 VPVL
+ 53 STKFG, 6 MNCFX, 46 VJHF, 81 HVMC, 68 CXFTF, 25 GNMV => 1 FUEL
+ 22 VJHF, 37 MNCFX => 5 FWMGM
+ 139 ORE => 4 NVRVD
+ 144 ORE => 7 JNWZP
+ 5 MNCFX, 7 RFSQX, 2 FWMGM, 2 VPVL, 19 CXFTF => 3 HVMC
+ 5 VJHF, 7 MNCFX, 9 VPVL, 37 CXFTF => 6 GNMV
+ 145 ORE => 6 MNCFX
+ 1 NVRVD => 8 CXFTF
+ 1 VJHF, 6 MNCFX => 4 RFSQX
+ 176 ORE => 6 VJHF";
+ let reactions = parse(input);
+ let ore_per_fuel = ore_needed_per_fuel(&reactions);
+ assert_eq!(fuel_produced(&reactions, 1_000_000_000_000, ore_per_fuel), 5_586_022);
+ }
+
+ #[test]
+ fn part2_sample_3() {
+ let input =
+ "171 ORE => 8 CNZTR
+ 7 ZLQW, 3 BMBT, 9 XCVML, 26 XMNCP, 1 WPTQ, 2 MZWV, 1 RJRHP => 4 PLWSL
+ 114 ORE => 4 BHXH
+ 14 VRPVC => 6 BMBT
+ 6 BHXH, 18 KTJDG, 12 WPTQ, 7 PLWSL, 31 FHTLT, 37 ZDVW => 1 FUEL
+ 6 WPTQ, 2 BMBT, 8 ZLQW, 18 KTJDG, 1 XMNCP, 6 MZWV, 1 RJRHP => 6 FHTLT
+ 15 XDBXC, 2 LTCX, 1 VRPVC => 6 ZLQW
+ 13 WPTQ, 10 LTCX, 3 RJRHP, 14 XMNCP, 2 MZWV, 1 ZLQW => 1 ZDVW
+ 5 BMBT => 4 WPTQ
+ 189 ORE => 9 KTJDG
+ 1 MZWV, 17 XDBXC, 3 XCVML => 2 XMNCP
+ 12 VRPVC, 27 CNZTR => 2 XDBXC
+ 15 KTJDG, 12 BHXH => 5 XCVML
+ 3 BHXH, 2 VRPVC => 7 MZWV
+ 121 ORE => 7 VRPVC
+ 7 XCVML => 6 RJRHP
+ 5 BHXH, 4 VRPVC => 5 LTCX";
+ let reactions = parse(input);
+ let ore_per_fuel = ore_needed_per_fuel(&reactions);
+ assert_eq!(fuel_produced(&reactions, 1_000_000_000_000, ore_per_fuel), 460_664);
}
}
\ No newline at end of file
projects / advent_of_code_2019.git / commitdiff