From e9a514409565c17a4a86e8c6402be8d7a4f399ae Mon Sep 17 00:00:00 2001
From: Justin Worthe <justin@worthe-it.co.za>
Date: Wed, 22 May 2019 20:38:47 +0200
Subject: Added a strategy cache for reusing previous round data

---
 src/bin/benchmark.rs |  2 +-
 src/game.rs          | 12 ++++++------
 src/main.rs          |  8 ++++++--
 src/strategy.rs      | 39 ++++++++++++++++++++++++++++++---------
 4 files changed, 43 insertions(+), 18 deletions(-)

(limited to 'src')

diff --git a/src/bin/benchmark.rs b/src/bin/benchmark.rs
index 794ba4e..20f74d0 100644
--- a/src/bin/benchmark.rs
+++ b/src/bin/benchmark.rs
@@ -13,7 +13,7 @@ fn main() {
     match json::read_state_from_json_file(&Path::new(&format!("./tests/example-state.json"))) {
         Ok(json_state) => {
             let new_board = game::GameBoard::new(json_state);
-            let _ = choose_move(&new_board, &start_time, max_time);
+            let _ = choose_move(&new_board, None, &start_time, max_time);
         },
         Err(e) => {
             eprintln!("WARN: State file could not be parsed: {}", e);
diff --git a/src/game.rs b/src/game.rs
index e3fb5c0..fe54f40 100644
--- a/src/game.rs
+++ b/src/game.rs
@@ -80,7 +80,7 @@ impl GameBoard {
     }
 
     pub fn update(&mut self, json: json::State) {
-        for w in json.my_player.worms {
+        for w in &json.my_player.worms {
             if let Some(worm) = self.players[0].find_worm_mut(w.id) {
                 worm.health = w.health;
                 worm.position = Point2d::new(w.position.x, w.position.y);
@@ -105,15 +105,15 @@ impl GameBoard {
                 self.map.clear(Point2d::new(cell.x, cell.y))
             }
         }
-        
-        self.round += 1;
-        debug_assert_eq!(json.current_round, self.round);
-        
-        // Remove dead worms and update active worm
+
         for player in &mut self.players {
             player.clear_dead_worms();
             player.next_active_worm();
         }
+        debug_assert_eq!(json.active_worm_index().unwrap(), self.players[0].active_worm);
+
+        self.round += 1;
+        debug_assert_eq!(json.current_round, self.round);
     }
 
     pub fn simulate(&mut self, moves: [Command; 2]) {
diff --git a/src/main.rs b/src/main.rs
index c24565a..b898fb5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -12,6 +12,7 @@ use steam_powered_wyrm::game;
 fn main() {
     let max_time = Duration::milliseconds(950);
     let mut game_board = None;
+    let mut strategy_cache = None;
     for line in stdin().lock().lines() {
         let start_time = PreciseTime::now();
         
@@ -23,13 +24,16 @@ fn main() {
                     match &mut game_board {
                         None => {
                             let new_board = game::GameBoard::new(json_state);
-                            let command = choose_move(&new_board, &start_time, max_time);
+                            let (command, cache) = choose_move(&new_board, strategy_cache, &start_time, max_time);
+                            strategy_cache = Some(cache);
                             game_board = Some(new_board);
                             command
                         },
                         Some(game_board) => {
                             game_board.update(json_state);
-                            choose_move(&game_board, &start_time, max_time)
+                            let (command, cache) = choose_move(&game_board, strategy_cache, &start_time, max_time);
+                            strategy_cache = Some(cache);
+                            command
                         }
                     }
                 },
diff --git a/src/strategy.rs b/src/strategy.rs
index 8d2eea5..39bbe66 100644
--- a/src/strategy.rs
+++ b/src/strategy.rs
@@ -11,13 +11,30 @@ use rand;
 use rand::prelude::*;
 use arrayvec::ArrayVec;
 
-pub fn choose_move(state: &GameBoard, start_time: &PreciseTime, max_time: Duration) -> Command {
-    let mut root_node = Node {
-        state: state.clone(),
-        score_sum: ScoreSum::new(),
-        player_score_sums: [HashMap::new(), HashMap::new()],
-        unexplored: mcts_move_combo(state),
-        children: HashMap::new(),
+pub fn choose_move(state: &GameBoard, previous_root: Option<Node>, start_time: &PreciseTime, max_time: Duration) -> (Command, Node) {
+    let mut root_node = match previous_root {
+        None => Node {
+            state: state.clone(),
+            score_sum: ScoreSum::new(),
+            player_score_sums: [HashMap::new(), HashMap::new()],
+            unexplored: mcts_move_combo(state),
+            children: HashMap::new(),
+        },
+        Some(mut node) => {
+            node.children.drain()
+                .map(|(_k, n)| n)
+                .find(|n| n.state == *state)
+                .unwrap_or_else(|| {
+                    eprintln!("Previous round did not appear in the cache");
+                    Node {
+                        state: state.clone(),
+                        score_sum: ScoreSum::new(),
+                        player_score_sums: [HashMap::new(), HashMap::new()],
+                        unexplored: mcts_move_combo(state),
+                        children: HashMap::new(),
+                    }
+                })
+        }        
     };
 
     while start_time.to(PreciseTime::now()) < max_time {
@@ -34,10 +51,14 @@ pub fn choose_move(state: &GameBoard, start_time: &PreciseTime, max_time: Durati
         );
     }
 
-    best_player_move(&root_node)
+    let chosen_command = best_player_move(&root_node);
+
+    root_node.children.retain(|[c1, _], _| *c1 == chosen_command);
+        
+    (chosen_command, root_node)
 }
 
-struct Node {
+pub struct Node {
     state: GameBoard,
     score_sum: ScoreSum,
     player_score_sums: [HashMap<Command, ScoreSum>; 2],
-- 
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