minimax logic, dynamic move getters

1 files changed, 49 insertions, 2 deletions

diff --git a/ttt.c b/ttt.c
index 843f6a3..c6f63e4 100644
--- a/ttt.c
+++ b/ttt.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 void draw_board(int boardState[3][3]) {
 	for(int r = 0; r < 3; r++) {
 		char* line = calloc(3, 1);
@@ -103,7 +104,7 @@ int get_game_state(int boardState[3][3]) {
 		return 0;
 	}
 }
-int* user_input_pos() {
+int* user_input_pos(int boardState[3][3], int turn) {
 	int* ip = malloc(2 * sizeof(int));
 	printf("Enter X coordinate");
 	scanf("%d", &ip[0]); 
@@ -111,6 +112,51 @@ int* user_input_pos() {
 	scanf("%d", &ip[1]); 
 	return ip;
 }
+struct PosInfo {
+	int* pos;
+	int eval;
+};
+struct PosInfo minimax(int boardState[3][3], int turn) {
+	int eval;
+	int* bestMove = calloc(2, sizeof(int));
+	int s = get_game_state(boardState);
+	if(s == turn + 1) {
+		eval = 10;
+	}
+	else if(s == (!turn) + 1) {
+		eval = -10;
+	}
+	else if(s == 4) {
+		eval = 0;
+	}
+	else {
+		int eval = 0;
+		for(int r = 0; r < 2; r++) {
+			for(int c = 0; c < 2; c++) {
+				int[3][3] simBoard;
+				memcpy(simBoard, boardState, sizeof(boardState));
+				if(simBoard[c][r] == 0) {
+					simBoard[c][r] = turn + 1;
+					struct PosInfo i = minimax(simBoard, !turn);
+					if(i.eval > eval) {
+						eval = i.eval;
+						bestMove[0] = c;
+						bestMove[1] = r;
+					}
+				}
+			}
+		}
+	}
+	//don't forget to clean up bestmove pointers
+	struct PosInfo posInfo;
+	posInfo.eval = eval;
+	posInfo.pos = bestMove; 
+	return posInfo;
+}
+int* ai_input_pos(int boardState[3][3], int turn) {
+	struct PosInfo i = minimax(boardState, turn);
+	return i.pos;
+}
 void clear_screen()
 {
     system("@cls||clear");
@@ -118,10 +164,11 @@ void clear_screen()
 int main() {
 	int board[3][3] = { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 } };
 	int turn = 0;
+	int* (*get_move_ptrs[2])(int[3][3], int) = { &user_input_pos, &ai_input_pos };
 	while(1) {
 		clear_screen();
 		draw_board(board);
-		int* tl = user_input_pos();
+		int* tl = get_move_ptrs[turn](board, turn);
 		board[tl[0] - 1][3 - tl[1]] = turn + 1;
 		free(tl);
 		int s = get_game_state(board);