[fix] Non heuristic moves...

src/main.cpp

@@ -121,6 +121,7 @@ bool checkGameEnd();
 void updateThinkingVisuals(int8_t pColor, int8_t column);
 void animateDrop(int col, int player);
 void moveDiscToCol(int startCol, int targetCol, int player, int speed);
+int evaluateBoard(int8_t aiP, int8_t huP);
 int minimax(int depth, int alpha, int beta, bool isMax, int8_t aiP, int8_t huP, int8_t rootCol);
 void performAiMove(int8_t aiP);
 void randomizeDemoPlies();
@@ -265,6 +266,39 @@ int8_t scanBoard() {
     return 0;
 }
 
+int evaluateBoard(int8_t aiP, int8_t huP) {
+    int score = 0;
+
+    // Center column bonus
+    for (int r = 0; r < ROWS; r++) {
+        if (board[3][r] == aiP) score += 3;
+        else if (board[3][r] == huP) score -= 3;
+    }
+
+    // Score a window of 4 cells by piece counts
+    auto scoreWindow = [&](int c, int r, int dc, int dr) -> int {
+        int ai = 0, hu = 0;
+        for (int i = 0; i < 4; i++) {
+            int8_t v = board[c + i * dc][r + i * dr];
+            if (v == aiP) ai++;
+            else if (v == huP) hu++;
+        }
+        if (ai > 0 && hu > 0) return 0;
+        if (ai == 3) return 50;
+        if (ai == 2) return 5;
+        if (hu == 3) return -50;
+        if (hu == 2) return -5;
+        return 0;
+    };
+
+    for (int r = 0; r < 6; r++) for (int c = 0; c < 4; c++) score += scoreWindow(c, r, 1, 0);
+    for (int r = 0; r < 3; r++) for (int c = 0; c < 7; c++) score += scoreWindow(c, r, 0, 1);
+    for (int r = 0; r < 3; r++) for (int c = 0; c < 4; c++) score += scoreWindow(c, r, 1, 1);
+    for (int r = 3; r < 6; r++) for (int c = 0; c < 4; c++) score += scoreWindow(c, r, 1, -1);
+
+    return score;
+}
+
 bool checkGameEnd() {
     winnerPlayer = scanBoard();
     bool won = winnerPlayer != 0;
@@ -331,7 +365,7 @@ int minimax(int depth, int alpha, int beta, bool isMax, int8_t aiP, int8_t huP,
     int8_t win = scanBoard();
     if (win == aiP) return 1000 + depth;
     if (win == huP) return -1000 - depth;
-    if (depth == 0 || isBoardFull()) return 0;
+    if (depth == 0 || isBoardFull()) return evaluateBoard(aiP, huP);
 
     int best = isMax ? -10000 : 10000;
     for (int c : colOrder) {
@@ -356,13 +390,22 @@ void performAiMove(int8_t aiP) {
     int originalPly = currentLookAhead;
     if (gameState == DEMO) currentLookAhead = demoPly[aiP - 1];
 
-    // Phase 1: always take an instant win or block an opponent's win
+    // Phase 1a: check ALL columns for instant AI win
     bool found = false;
     for (int c = 0; c < COLS && !found; c++) {
         int r = getFirstEmptyRow(c);
         if (r != -1) {
-            board[c][r] = aiP; if (scanBoard() == aiP) { board[c][r]=0; bestCol=c; found=true; break; }
-            board[c][r] = huP; if (scanBoard() == huP) { board[c][r]=0; bestCol=c; found=true; break; }
+            board[c][r] = aiP;
+            if (scanBoard() == aiP) { board[c][r] = 0; bestCol = c; found = true; break; }
+            board[c][r] = 0;
+        }
+    }
+    // Phase 1b: check ALL columns for opponent block
+    for (int c = 0; c < COLS && !found; c++) {
+        int r = getFirstEmptyRow(c);
+        if (r != -1) {
+            board[c][r] = huP;
+            if (scanBoard() == huP) { board[c][r] = 0; bestCol = c; found = true; break; }
             board[c][r] = 0;
         }
     }