From 890b5fe5682895fa73c6f53ca776e9138045dd9f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?F=C3=A9lix=20Lescaudey=20de=20Maneville?=
 <felix.maneville@gmail.com>
Date: Wed, 31 Jan 2024 09:43:15 +0100
Subject: [PATCH] More optimizations

---
 src/algorithms/field_of_movement.rs | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/algorithms/field_of_movement.rs b/src/algorithms/field_of_movement.rs
index 99cb381..d7b951c 100644
--- a/src/algorithms/field_of_movement.rs
+++ b/src/algorithms/field_of_movement.rs
@@ -67,16 +67,17 @@ pub fn field_of_movement(
     let mut computed_costs = HashMap::with_capacity(Hex::range_count(budget) as usize);
     computed_costs.insert(coord, 0);
 
-    // Optimization
-    let rings: Vec<_> = coord.rings(1..=budget).flatten().collect();
+    // We cache the rings and costs
+    let rings: Vec<(Hex, u32)> = coord
+        .rings(1..=budget)
+        .flatten()
+        .filter_map(|h| cost(h).map(|c| (h, c)))
+        .collect();
 
     let mut loop_again = true;
     while loop_again {
         loop_again = false;
-        for &coord in &rings {
-            let Some(coord_cost) = cost(coord) else {
-                continue;
-            };
+        for (coord, coord_cost) in &rings {
             let Some(neighbor_cost) = coord
                 .all_neighbors()
                 .into_iter()
@@ -86,7 +87,7 @@ pub fn field_of_movement(
                 continue;
             };
             let computed_cost = coord_cost + 1 + neighbor_cost;
-            let res = computed_costs.insert(coord, computed_cost);
+            let res = computed_costs.insert(*coord, computed_cost);
             if !loop_again && (res.is_none() || res != Some(computed_cost)) {
                 loop_again = true;
             }