uct/tree.h

   1 #ifndef ZZGO_UCT_TREE_H
   2 #define ZZGO_UCT_TREE_H
   3
   4 #include <stdbool.h>
   5 #include "move.h"
   6
   7 struct board;
   8 struct uct;
   9
  10 /*
  11  *            +------+
  12  *            | node |
  13  *            +------+
  14  *          / <- parent
  15  * +------+   v- sibling +------+
  16  * | node | ------------ | node |
  17  * +------+              +------+
  18  *    | <- children          |
  19  * +------+   +------+   +------+   +------+
  20  * | node | - | node |   | node | - | node |
  21  * +------+   +------+   +------+   +------+
  22  */
  23
  24 struct move_stats {
  25         int playouts; // # of playouts coming through this node
  26         int wins; // # of BLACK wins coming through this node
  27         float value; // wins/playouts
  28 };
  29
  30 struct tree_node {
  31         hash_t hash;
  32         struct tree_node *parent, *sibling, *children;
  33
  34         /*** From here on, struct is saved/loaded from opening book */
  35
  36         int depth; // just for statistics
  37
  38         coord_t coord;
  39
  40         struct move_stats u;
  41         struct move_stats prior;
  42         /* XXX: Should be way for policies to add their own stats */
  43         struct move_stats amaf;
  44         /* Stats before starting playout; used for multi-thread normalization. */
  45         struct move_stats pu, pamaf;
  46 #define NODE_HINT_NOAMAF 0x80
  47         int hints;
  48 };
  49
  50 struct tree {
  51         struct board *board;
  52         struct tree_node *root;
  53         struct board_symmetry root_symmetry;
  54         enum stone root_color;
  55
  56         // Statistics
  57         int max_depth;
  58 };
  59
  60 struct tree *tree_init(struct board *board, enum stone color);
  61 void tree_done(struct tree *tree);
  62 void tree_dump(struct tree *tree, int thres);
  63 void tree_save(struct tree *tree, struct board *b, int thres);
  64 void tree_load(struct tree *tree, struct board *b);
  65 struct tree *tree_copy(struct tree *tree);
  66 void tree_merge(struct tree *dest, struct tree *src);
  67 void tree_normalize(struct tree *tree, int factor);
  68
  69 void tree_expand_node(struct tree *tree, struct tree_node *node, struct board *b, enum stone color, int radar, struct uct *u, int parity);
  70 void tree_delete_node(struct tree *tree, struct tree_node *node);
  71 void tree_promote_node(struct tree *tree, struct tree_node *node);
  72 bool tree_promote_at(struct tree *tree, struct board *b, coord_t c);
  73
  74 static bool tree_leaf_node(struct tree_node *node);
  75 static void tree_update_node_value(struct tree_node *node);
  76
  77 /* Get black parity from parity within the tree. */
  78 #define tree_parity(tree, parity) \
  79         (tree->root_color == S_WHITE ? (parity) : -1 * (parity))
  80
  81 /* Get a value to maximize; @parity is parity within the tree. */
  82 #define tree_node_get_value(tree, node, type, parity) \
  83         (tree_parity(tree, parity) > 0 ? node->type.value : 1 - node->type.value)
  84 #define tree_node_get_wins(tree, node, type, parity) \
  85         (tree_parity(tree, parity) > 0 ? node->type.wins : node->type.playouts - node->type.wins)
  86
  87 static inline bool
  88 tree_leaf_node(struct tree_node *node)
  89 {
  90         return !(node->children);
  91 }
  92
  93 static inline void
  94 tree_update_node_value(struct tree_node *node)
  95 {
  96         bool noamaf = node->hints & NODE_HINT_NOAMAF;
  97         node->u.value = (float)(node->u.wins + node->prior.wins + (!noamaf ? node->amaf.wins : 0))
  98                         / (node->u.playouts + node->prior.playouts + (!noamaf ? node->amaf.playouts : 0));
  99 }
 100
 101 #endif