From 370a2bc1e592269eea86e3d3a0c0cab1201ad5a9 Mon Sep 17 00:00:00 2001
From: pasterp <pascal@phelipot.me>
Date: Tue, 12 Dec 2023 10:03:08 +0100
Subject: [PATCH] day5 part 2

---
 src/day5/mod.rs | 57 +++++++++++++++++++++++++++----------------------
 1 file changed, 32 insertions(+), 25 deletions(-)

diff --git a/src/day5/mod.rs b/src/day5/mod.rs
index 27a2033..8d1e71e 100644
--- a/src/day5/mod.rs
+++ b/src/day5/mod.rs
@@ -121,34 +121,41 @@ pub fn solve(lines: Vec<String>, part: Part) -> u64 {
         );
     }
 
-    if let Part::Two = part {
-        // Convert the seeds to the new format !
-        let original_seeds = dataset.seeds;
-        let mut new_seeds : Vec<u64> = Vec::new();
-
-        for chunk in original_seeds.chunks_exact(2) {
-            let range = chunk[0]..(chunk[0]+chunk[1]);
-            // FIXME : don't do that it will eat all your memory: new_seeds.append(&mut range.collect::<Vec<u64>>());
+    match part {
+        Part::One => {
+            let mut min_location = u64::MAX;
+            for seed in dataset.seeds {
+                let mut stage = "seed";
+                let mut value = seed;
+                while let Some(map) = dataset.maps.get(stage) {
+                    debug!("Stage {} -> {}", stage, map.target_domain);
+                    value = map.map(value);
+                    stage = &map.target_domain;
+                }
+                min_location = min_location.min(value);
+                info!("Final stage seed {} -> location {}", seed, value);
+            }
+            return min_location;
         }
-        debug!("New seeds: {:?}", new_seeds);
-
-        dataset.seeds = new_seeds;
-    }
-
-    let mut min_location = u64::MAX;
-    for seed in dataset.seeds {
-        let mut stage = "seed";
-        let mut value = seed;
-        while let Some(map) = dataset.maps.get(stage) {
-            debug!("Stage {} -> {}", stage, map.target_domain);
-            value = map.map(value);
-            stage = &map.target_domain;
+        Part::Two => {
+            let mut min_location = u64::MAX;
+            for chunk in dataset.seeds.chunks_exact(2) {
+                info!("Computing range {} -> {}", chunk[0], chunk[0] + chunk[1]);
+                for seed in chunk[0]..(chunk[0] + chunk[1]) {
+                    let mut stage = "seed";
+                    let mut value = seed;
+                    while let Some(map) = dataset.maps.get(stage) {
+                        debug!("Stage {} -> {}", stage, map.target_domain);
+                        value = map.map(value);
+                        stage = &map.target_domain;
+                    }
+                    min_location = min_location.min(value);
+                    trace!("Final stage seed {} -> location {}", seed, value);
+                }
+            }
+            return min_location;
         }
-        min_location = min_location.min(value);
-        info!("Final stage seed {} -> location {}", seed, value);
     }
-
-    min_location
 }
 
 #[cfg(test)]