adding transpositions

1 files changed, 19 insertions, 8 deletions

diff --git a/src/bot.cpp b/src/bot.cpp
index 1a156a2..8a570e4 100644
--- a/src/bot.cpp
+++ b/src/bot.cpp
@@ -1,14 +1,16 @@
 #include "bot.hpp"
 #include "board.hpp"
 #include "moves.hpp"
+#include "zobrist.hpp"
 #include <algorithm>
 #include <cassert>
 #include <cmath>
+#include <cstdint>
 #include <cstdlib>
 #include <iostream>
 #include <vector>
 
-const int SEARCH_DEPTH = 4;
+const int SEARCH_DEPTH = 5;
 
 const int PAWN_VALUE = 100;
 const int KNIGHT_VALUE = 320;
@@ -132,17 +134,25 @@ float minimax(int depth, Game *b, float alpha, float beta) {
   if (depth == 0) {
     return EvaluateBoardForWhite(b, depth);
   }
+  uint64_t gameHash = GenerateZobristKey(b);
+
+  if (b->Transpositions->contains(gameHash)) {
+    float value = b->Transpositions->at(gameHash);
+    return value;
+  }
   auto moves = GetLegalMoves(b);
   if (moves.size() == 0) {
     return EvaluateBoardForWhite(b, depth);
   }
+  float bestEval;
   if (b->turn) {
-    float bestEval = -INFINITY;
+    bestEval = -INFINITY;
 
     for (Move move : moves) {
       UndoMove undo = MakeMove(move, b);
 
       float eval = minimax(depth - 1, b, alpha, beta);
+
       UnMakeMove(undo, b);
       bestEval = std::max(bestEval, eval);
 
@@ -152,26 +162,27 @@ float minimax(int depth, Game *b, float alpha, float beta) {
         break;
       }
     }
-
-    return bestEval;
   } else {
-    float BestEval = INFINITY;
+    bestEval = INFINITY;
 
     for (Move move : moves) {
 
       UndoMove undo = MakeMove(move, b);
 
       float eval = minimax(depth - 1, b, alpha, beta);
+
       UnMakeMove(undo, b);
-      BestEval = std::min(BestEval, eval);
+      bestEval = std::min(bestEval, eval);
 
-      beta = std::min(beta, BestEval);
+      beta = std::min(beta, bestEval);
       if (alpha >= beta) {
         break; // *snips*
       }
     }
-    return BestEval;
   }
+
+  b->Transpositions->operator[](gameHash) = bestEval;
+  return bestEval;
 }
 int PSTIndex(int square, bool white) { return white ? square : (56 ^ square); }