5 files changed, 38 insertions, 14 deletions
diff --git a/src/board.hpp b/src/board.hpp
index 9418571..687510e 100644
--- a/src/board.hpp
+++ b/src/board.hpp
@@ -46,6 +46,7 @@ struct Game {
   bool canEnpassant = 0;
   GameState state = TURN;
   std::unordered_map<uint64_t, int> ThreeFoldMap;
+  std::unordered_map<uint64_t, float> *Transpositions = nullptr;
 };
 
 struct Move {
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); }
 
diff --git a/src/main.cpp b/src/main.cpp
index 8a1821e..0bdd150 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4,6 +4,8 @@
 #include <cstdlib>
 #include <ctime>
 
+using namespace std;
+
 int main() {
   InitZobrist();
   srand(time(0));
diff --git a/src/uci.cpp b/src/uci.cpp
index 4e32d6f..b4e384a 100644
--- a/src/uci.cpp
+++ b/src/uci.cpp
@@ -15,6 +15,7 @@
 #include <chrono>
 #include <fstream>
 #include <iomanip>
+#include <unordered_map>
 
 std::ofstream uciLog("uci_log.txt", std::ios::app);
 
@@ -44,7 +45,8 @@ Move UciToMove(string uci) {
 
   return {from, to};
 }
-static Game initBoard(string startingFEN) {
+Game initBoard(string startingFEN,
+               std::unordered_map<uint64_t, float> *transPositions) {
   Game b{};
   b.enPassant = IndexToPosition(0); // default value
   b.canEnpassant = false;
@@ -53,7 +55,7 @@ static Game initBoard(string startingFEN) {
   b.castle = "";
   b.halfMoveClock = 0;
   b.MoveClock = 0;
-  setBoardFen(startingFEN, &b);
+  b.Transpositions = transPositions;
 
   Piece EmptyPiece = {
       false,
@@ -64,11 +66,15 @@ static Game initBoard(string startingFEN) {
     b.pieces[i] = EmptyPiece;
   };
 
+  setBoardFen(startingFEN, &b);
+
   return b;
 };
 void Uci() {
+  unordered_map<uint64_t, float> transpositions = {};
   Game game =
-      initBoard("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
+      initBoard("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
+                &transpositions);
 
   string line;
 
@@ -85,7 +91,8 @@ void Uci() {
       cout.flush();
     } else if (cmd == "ucinewgame") {
       game =
-          initBoard("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
+          initBoard("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
+                    &transpositions);
     } else if (cmd == "isready") {
       cout << "readyok\n";
       cout.flush();
@@ -126,7 +133,8 @@ void Uci() {
 
       if (token == "startpos") {
         game = initBoard(
-            "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1");
+            "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
+            &transpositions);
       } else if (token == "fen") {
         string fen;
         string part;
@@ -139,7 +147,7 @@ void Uci() {
           fen += part;
         }
 
-        game = initBoard(fen);
+        game = initBoard(fen, &transpositions);
       }
 
       // check for moves
diff --git a/src/uci.hpp b/src/uci.hpp
index 4d0a91b..4d84215 100644
--- a/src/uci.hpp
+++ b/src/uci.hpp
@@ -7,4 +7,6 @@
 Move UciToMove(std::string uci);
 void LogUci(const std::string &message);
 void Uci();
+Game initBoard(std::string startingFEN,
+               std::unordered_map<uint64_t, float> *transPositions);
 #endif /* SRC_UCI_H_ */