From 343a6e8cf000b57d1e571da6d58689a13f6abc8f Mon Sep 17 00:00:00 2001
From: Mylloon <kennel.anri@tutanota.com>
Date: Fri, 31 Mar 2023 16:39:27 +0200
Subject: [PATCH] * rework of selection * don't override nbmove to 0 * fix typo
 in simulation not playing * fix win verification * fix backpropagation * use
 iterator instead of time for algo limitation (MEMORY LEAK?) * remove debug
 prints

---
 TP2/includes/mybt.h |  5 +--
 TP2/src/mybt.cpp    | 95 +++++++++++++++++++++------------------------
 2 files changed, 46 insertions(+), 54 deletions(-)

diff --git a/TP2/includes/mybt.h b/TP2/includes/mybt.h
index aec3449..7202ff0 100644
--- a/TP2/includes/mybt.h
+++ b/TP2/includes/mybt.h
@@ -1,7 +1,6 @@
 #ifndef MYBT_H
 #define MYBT_H
 
-#include <chrono>
 #include <random>
 
 #define WHITE 0
@@ -103,8 +102,8 @@ struct bt_t {
   // MCTS
   bt_node_t *mcts_selection(bt_node_t *);
   void mcts_expansion(bt_node_t *);
-  bool mcts_simulation(bt_node_t *);
-  void mcts_back_propagation(bt_node_t *, bool);
+  bool mcts_simulation();
+  static void mcts_back_propagation(bt_node_t *, bool);
 
   void add_move(int _li, int _ci, int _lf, int _cf) {
     moves[nb_moves].line_i = _li;
diff --git a/TP2/src/mybt.cpp b/TP2/src/mybt.cpp
index 032c653..848a1e2 100644
--- a/TP2/src/mybt.cpp
+++ b/TP2/src/mybt.cpp
@@ -193,29 +193,39 @@ bt_move_t bt_t::get_rand_move() {
 }
 
 bt_node_t *bt_t::mcts_selection(bt_node_t *node) {
-  if (node->nb_simulation > 0) {
-    bt_node_t *best = nullptr;
-    float score = std::numeric_limits<float>::lowest();
-    for (auto i : node->children) {
-      // https://en.wikipedia.org/wiki/Monte_Carlo_tree_search#Exploration_and_exploitation
-      float curr_score =
-          static_cast<float>(i->wins) / i->nb_simulation +
-          sqrt(2) * sqrt(log(node->nb_simulation) / i->nb_simulation);
-      if (curr_score > score) {
-        best = i;
-        score = curr_score;
-      }
-    }
-    // Return the element with the higher score
-    return best;
-  } else {
-    // Return random element if no simulation already done
-    return node
-        ->children[(static_cast<int>(rand())) % (node->children.size() - 1)];
+  // Play the move is game over or first call
+  if ((endgame() != EMPTY) ||
+      ((node->nb_simulation == 0) && (node->parent != nullptr))) {
+    play(node->move);
+    return node;
   }
+
+  bt_node_t *best = nullptr;
+  float score = std::numeric_limits<float>::lowest();
+  for (auto i : node->children) {
+    // Play the move if never played
+    if (i->nb_simulation == 0) {
+      play(i->move);
+
+      return i;
+    }
+
+    // https://en.wikipedia.org/wiki/Monte_Carlo_tree_search#Exploration_and_exploitation
+    float curr_score =
+        (static_cast<float>(i->wins) / i->nb_simulation) +
+        ((sqrt(2) * sqrt(log(node->nb_simulation)) / i->nb_simulation));
+
+    if (curr_score > score) {
+      best = i;
+      score = curr_score;
+    }
+  }
+
+  play(best->move);
+  return mcts_selection(best);
 }
 
-void bt_t::mcts_expansion(bt_node_t *root) {
+void bt_t::mcts_expansion(bt_node_t *node) {
   update_moves();
 
   for (int i = 0; i < nb_moves; i++) {
@@ -223,32 +233,29 @@ void bt_t::mcts_expansion(bt_node_t *root) {
     bt_node_t *tmp = new bt_node_t;
     tmp->move = moves[i];
     tmp->wins = 0;
-    tmp->parent = root;
+    tmp->parent = node;
     tmp->nb_simulation = 0;
 
-    // Add child to root
-    root->children.push_back(tmp);
+    // Add child to selected node
+    node->children.push_back(tmp);
   }
-
-  // Avoid re-add same moves
-  nb_moves = 0;
 }
 
-bool bt_t::mcts_simulation(bt_node_t *node) {
+bool bt_t::mcts_simulation(void) {
   int me = (turn % 2 == 0) ? WHITE : BLACK;
 
   // then play randomly 'til the game is over
-  while (endgame() != EMPTY) {
+  while (endgame() == EMPTY) {
     play(get_rand_move());
   }
 
   // if i won
-  return ((turn % 2 == 0) ? WHITE : BLACK == me) ? true : false;
+  return ((turn % 2 == 0) ? WHITE : BLACK) == me ? true : false;
 }
 
 void bt_t::mcts_back_propagation(bt_node_t *simulated, bool won) {
   // propagate values to the top of the tree
-  while (simulated->parent != nullptr) {
+  while (simulated != nullptr) {
     if (won) {
       simulated->wins++;
     }
@@ -276,40 +283,26 @@ bt_move_t bt_t::get_mcts_move(double max_time) {
   tree->children = {};
   tree->wins = 0;
   tree->nb_simulation = 0;
-  print_vec(*this, tree->children);
-  mcts_expansion(tree);
-  print_vec(*this, tree->children);
 
-  // Time constraint
-  auto now = std::chrono::steady_clock::now();
-  std::chrono::duration<double> elapsed{};
+  // On populise l'arbre avec les entrées de départ
+  mcts_expansion(tree);
 
   // MCTS
-  while (elapsed.count() < max_time) {
+  for (int it = 0; it < 200; ++it) {
     // Copy board
     bt_t copy_b = *this;
 
     // Selection
-    bt_node_t *selected = copy_b.mcts_selection(tree);
-
-    // Play the move
-    if (can_play(selected->move)) {
-      play(selected->move);
-    } else {
-      fprintf(stderr, "?????\n");
-    }
+    bt_node_t *result = copy_b.mcts_selection(tree);
 
     // Expansion
-    copy_b.mcts_expansion(selected);
+    copy_b.mcts_expansion(result);
 
     // Simulation
-    bool is_win = copy_b.mcts_simulation(selected);
+    bool is_win = copy_b.mcts_simulation();
 
     // Update
-    mcts_back_propagation(selected, is_win);
-
-    // Update elapsed time
-    elapsed = std::chrono::steady_clock::now() - now;
+    mcts_back_propagation(result, is_win);
   }
 
   // Select best move