Finally, part 2 for Day 19 2022

3 files changed, 31 insertions, 8 deletions

diff --git a/2022/19/a.rs b/2022/19/a.rs
index 898debd..371d356 100644
--- a/2022/19/a.rs
+++ b/2022/19/a.rs
@@ -4,7 +4,7 @@ use common::*;
 
 fn main() {
     const MINUTES: i32 = 24;
-    let mut mem = HashMap::<(Status, i32), i32>::new();
+    let mut mem = HashMap::<(Status, i32), i64>::new();
     let mut i = 1;
     let mut sum = 0;
     for bp in read_blueprints_from_stdin() {
diff --git a/2022/19/b.rs b/2022/19/b.rs
new file mode 100644
index 0000000..d97bf53
--- /dev/null
+++ b/2022/19/b.rs
@@ -0,0 +1,17 @@
+use std::collections::HashMap;
+mod common;
+use common::*;
+
+fn main() {
+    const MINUTES: i32 = 32;
+    let mut mem = HashMap::<(Status, i32), i64>::new();
+    let mut prod = 1;
+    let bp = read_blueprints_from_stdin();
+    for i in 0..3 {
+        let mg = most_geodes(&bp[i], &Status::new(), MINUTES, &mut mem);
+        println!("{i}: {mg}");
+        prod *= mg;
+        mem.clear();
+    }
+    println!("{prod}");
+}
diff --git a/2022/19/common.rs b/2022/19/common.rs
index 95b9a2d..c4177ac 100644
--- a/2022/19/common.rs
+++ b/2022/19/common.rs
@@ -63,7 +63,7 @@ pub struct Blueprint {
     ore_bot_cost: Stock,
     cla_bot_cost: Stock,
     obs_bot_cost: Stock,
-    geo_bot_cost: Stock
+    geo_bot_cost: Stock,
 }
 
 impl Blueprint {
@@ -118,8 +118,8 @@ pub fn most_geodes(
     bp: &Blueprint,
     s: &Status,
     m: i32,
-    mem: &mut HashMap<(Status, i32), i32>
-) -> i32 {
+    mem: &mut HashMap<(Status, i32), i64>
+) -> i64 {
     if m <= 1 { return 0; }
 
     if let Some(r) = mem.get(&(s.clone(), m)) { return *r; }
@@ -130,16 +130,22 @@ pub fn most_geodes(
     // 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 + most_geodes(bp, &new_status, m-1, mem);
+        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;
 
-    let can_obs = s.resources >= bp.obs_bot_cost;
-    let can_cla = s.resources >= bp.cla_bot_cost;
-    let can_ore = s.resources >= bp.ore_bot_cost;
+    // 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;