From 74becec945c19bad637cb2760ca30da9b4d395f8 Mon Sep 17 00:00:00 2001
From: Justin Worthe <justin@worthe-it.co.za>
Date: Fri, 9 Aug 2019 17:37:24 +0200
Subject: Removed unnecessary clone

---
 src/strategy/minimax.rs | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/strategy/minimax.rs b/src/strategy/minimax.rs
index 7cc4918..2dcd7bd 100644
--- a/src/strategy/minimax.rs
+++ b/src/strategy/minimax.rs
@@ -36,7 +36,7 @@ pub fn choose_move(
     };
 
     while start_time.to(PreciseTime::now()) < max_time {
-        let _ = expand_tree(&mut root_node, &state);
+        let _ = expand_tree(&mut root_node, state.clone());
     }
 
     eprintln!("Number of simulations: {}", root_node.score_sum.visit_count);
@@ -124,16 +124,15 @@ impl AddAssign<Score> for ScoreSum {
     }
 }
 
-fn expand_tree(node: &mut Node, state: &GameBoard) -> Score {
+fn expand_tree(node: &mut Node, mut state: GameBoard) -> Score {
     if state.outcome != SimulationOutcome::Continue {
-        score(state)
+        score(&state)
     } else if let Some(commands) = node.unexplored.pop() {
         // TODO: Explore preemptively doing the rollout
-        let mut new_state = state.clone();
-        new_state.simulate(commands);
-        let score = score(&new_state);
-        let unexplored = if new_state.outcome == SimulationOutcome::Continue {
-            move_combos(&new_state)
+        state.simulate(commands);
+        let score = score(&state);
+        let unexplored = if state.outcome == SimulationOutcome::Continue {
+            move_combos(&state)
         } else {
             Vec::new()
         };
@@ -191,16 +190,12 @@ fn expand_tree(node: &mut Node, state: &GameBoard) -> Score {
         score
     } else {
         let commands = choose_existing(node);
-        // TODO: Is there anyway I can avoid this clone? Clone before
-        // calling update_tree and just pass ownership all the way
-        // down.
-        let mut new_state = state.clone();
-        new_state.simulate(commands);
+        state.simulate(commands);
         let score = expand_tree(
             node.children
                 .get_mut(&commands)
                 .expect("The existing node hasn't been tried yet"),
-            &new_state,
+            state,
         );
         update(node, commands, score);
         score
@@ -240,7 +235,8 @@ fn score(state: &GameBoard) -> Score {
     const POINTS_WEIGHT: f32 = 0.;
     const VICTORY_WEIGHT: f32 = 3000.;
 
-    // TODO: Try adding new features here, like max worm health, weighted in some way
+    // TODO: Try adding new features here, like total player health, living worms, etc
+    // TODO: Calibrate these weightings somehow?
     // TODO: Distance to dirt heatmap? Probably less relevant these days.
     Score {
         val: match state.outcome {
-- 
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