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// This works for part 1, but it is too slow for part 2.
// May be I am doing something wrong with caching?
use std::cmp::{max, Ordering};
use std::ops::{AddAssign, SubAssign};
use std::collections::HashMap;
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct Stock {
pub ore: i32,
pub cla: i32,
pub obs: i32
}
impl Stock {
pub fn all_lower(&self, other: &Self) -> bool {
self.ore <= other.ore && self.cla <= other.cla && self.obs <= other.obs
}
}
impl PartialOrd for Stock {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
if self == other { return Some(Ordering::Equal); }
if self.all_lower(other) { return Some(Ordering::Less); }
if other.all_lower(self) { return Some(Ordering::Greater); }
None
}
}
impl AddAssign<&Stock> for Stock {
fn add_assign(&mut self, other: &Self) {
self.ore += other.ore;
self.cla += other.cla;
self.obs += other.obs;
}
}
impl SubAssign<&Stock> for Stock {
fn sub_assign(&mut self, other: &Self) {
self.ore -= other.ore;
self.cla -= other.cla;
self.obs -= other.obs;
}
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct Status {
pub bots: Stock,
pub resources: Stock
}
impl Status {
pub fn new() -> Status {
Status {
bots: Stock { ore: 1, cla: 0, obs: 0 },
resources: Stock { ore: 0, cla: 0, obs: 0 }
}
}
}
#[derive(Debug, Clone, Hash)]
pub struct Blueprint {
ore_bot_cost: Stock,
cla_bot_cost: Stock,
obs_bot_cost: Stock,
geo_bot_cost: Stock,
}
impl Blueprint {
fn parse_one_resource(line: &str, i: &mut usize) -> i32 {
*i = line[*i..].find("costs ").unwrap() + 6 + *i;
let j = line[*i..].find(' ').unwrap() + *i;
line[*i..j].parse::<i32>().unwrap()
}
fn parse_two_resources(line: &str, i: &mut usize) -> (i32, i32) {
*i = line[*i..].find("costs ").unwrap() + 6 + *i;
let j = line[*i..].find(' ').unwrap() + *i;
let a = line[*i..j].parse::<i32>().unwrap();
*i = line[*i..].find("and ").unwrap() + 4 + *i;
let j = line[*i..].find(' ').unwrap() + *i;
let b = line[*i..j].parse::<i32>().unwrap();
(a, b)
}
pub fn from_line(line: &str) -> Blueprint {
let mut i = 0;
let ore = Blueprint::parse_one_resource(&line, &mut i);
let ore_bot_cost = Stock { ore, cla: 0, obs: 0 };
let ore = Blueprint::parse_one_resource(&line, &mut i);
let cla_bot_cost = Stock { ore, cla: 0, obs: 0 };
let (ore, cla) = Blueprint::parse_two_resources(&line, &mut i);
let obs_bot_cost = Stock { ore, cla, obs: 0 };
let (ore, obs) = Blueprint::parse_two_resources(&line, &mut i);
let geo_bot_cost = Stock { ore, cla: 0, obs };
Blueprint { ore_bot_cost, cla_bot_cost, obs_bot_cost, geo_bot_cost }
}
}
pub fn read_blueprints_from_stdin() -> Vec<Blueprint> {
let mut v = vec![];
let mut line = String::new();
while std::io::stdin().read_line(&mut line).unwrap() > 0 {
v.push(Blueprint::from_line(&line));
line.clear();
}
v
}
pub fn most_geodes(
bp: &Blueprint,
s: &Status,
m: i32,
mem: &mut HashMap<(Status, i32), i64>
) -> i64 {
if m <= 1 { return 0; }
if let Some(r) = mem.get(&(s.clone(), m)) { return *r; }
let mut new_status = s.clone();
new_status.resources += &new_status.bots;
// If a geode bot can be built, it is always the best thing to do
if m > 1 && s.resources >= bp.geo_bot_cost {
new_status.resources -= &bp.geo_bot_cost;
let result = (m - 1) as i64 + most_geodes(bp, &new_status, m-1, mem);
mem.insert((s.clone(), m), result);
return result;
}
let mut result = 0;
// The second check is to avoid producing too many bots for each given
// type of resource. For example, 5 ore bots will produce more ore
// than the factory can ever consume, since all bots cost at most 4 ore.
let can_obs = s.resources >= bp.obs_bot_cost &&
s.bots.obs < bp.geo_bot_cost.obs;
let can_cla = s.resources >= bp.cla_bot_cost &&
s.bots.cla < bp.obs_bot_cost.cla;
let can_ore = s.resources >= bp.ore_bot_cost &&
s.bots.ore < 4;
if m > 2 && can_obs {
new_status.resources -= &bp.obs_bot_cost;
new_status.bots.obs += 1;
result = max(result, most_geodes(bp, &new_status, m-1, mem));
new_status.bots.obs -= 1;
new_status.resources += &bp.obs_bot_cost;
}
if m > 3 && can_cla {
new_status.resources -= &bp.cla_bot_cost;
new_status.bots.cla += 1;
result = max(result, most_geodes(bp, &new_status, m-1, mem));
new_status.bots.cla -= 1;
new_status.resources += &bp.cla_bot_cost;
}
if m > 4 && can_ore {
new_status.resources -= &bp.ore_bot_cost;
new_status.bots.ore += 1;
result = max(result, most_geodes(bp, &new_status, m-1, mem));
new_status.bots.ore -= 1;
new_status.resources += &bp.ore_bot_cost;
}
if !can_obs || !can_cla || !can_ore {
result = max(result, most_geodes(bp, &new_status, m-1, mem));
}
mem.insert((s.clone(), m), result);
result
}
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