### Random choice for game bot

Hi guys, so my homework is to make a tic-tac-toe game, and when I was trying to make a bot to play against the player, I realized that my programming way make the bot always prioritize some move, I wonder if someone know how to make my bot randomly choose one of the options when making a move.

I think about use random number and assign it to the move but when the condition to make the move do not meet, it will take a long time to run

 ``1234567891011121314151617181920212223242526272829303132333435363738394041424344454647`` `````` int AI_move(int i, setting_game setting, int playerturn) { int move; if (player[i].difficulty == 1) return AI_move_random(setting, playerturn); if (player[i].difficulty == 2) { if (playerturn == 1) move = AI_move_random(setting, playerturn); else if (playerturn == 2) move = AI_move_near(i, playerturn); else if (playerturn >= 3) { move = AI_move_win_vertical(i, playerturn); if (move == 0) move = AI_move_win_horizontal(i, playerturn); if (move == 0) move = AI_move_win_diagonal_left(i, playerturn); if (move == 0) move = AI_move_win_diagonal_right(i, playerturn); if (move == 0) move = AI_move_near(i, playerturn); if (move == 0) move = AI_move_random(setting, playerturn); } return move; } if (player[i].difficulty == 3) { if (playerturn == 1) move = AI_move_random(setting, playerturn); else if (playerturn == 2) move = AI_move_near(i, playerturn); else if (playerturn >= 3) { if (move == 0) move = AI_move_block_horizontal(i, playerturn); if (move == 0) move = AI_move_block_vertical(i, playerturn); if (move == 0) move = AI_move_block_diagonal_left(i, playerturn); if (move == 0) move = AI_move_block_diagonal_right(i, playerturn); if (move == 0) move = AI_move_win_vertical(i, playerturn); if (move == 0) move = AI_move_win_horizontal(i, playerturn); if (move == 0) move = AI_move_win_diagonal_left(i, playerturn); if (move == 0) move = AI_move_win_diagonal_right(i, playerturn); if (move == 0) move = AI_move_near(i, playerturn); if (move == 0) move = AI_move_random(setting, playerturn); } cout << move; return move; } ``````
vector <int> moves;
... push back valid moves
... randomly pick from 0 to size in move vector.

there are 9 moves on an empty board, and it goes down from there.
it should not take more than 9 decisions to find a move, then... it should be very, very fast.
at any given time, not counting the first move, there should only be 2-3 moves that make any sense at all. Often, you have 1 move or lose.

TTT is often used to show transposition table AI -- turns out there are very few board positions once you realize that mirrored and rotated boards are the same solution as their counterpart(s).
Last edited on
@jonnin
Unfortunately that I do not be allowed to use vector in this assignment, and my board is free-size, many loops in each move to find a correct position :v
free sized board is an issue, but vector can be replaced by whatever you like, array or linked list or even a string. its the approach that matters, not the specific tool you use to make it so.
stow the moves, and randomly pick one, however you like. Vector is just the default/typical way if you can use modern C++.
There is no need for a container to store the moves. Count the number of available moves and pick a random move number; convert that random move number to a row, col pair.

Something like this:

 ``12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849`` ``````#include #include int random_int( int minv, int maxv ) // generate a random integer in [minv,maxv] { static std::mt19937 rng( std::random_device{}() ) ; static std::uniform_int_distribution distrib ; using param_type = decltype(distrib)::param_type ; distrib.param( param_type{ minv, maxv } ) ; return distrib(rng) ; } enum cell : char { SPACE = ' ', NOUGHT = 'O', CROSS = 'X' }; constexpr int MAX_SZ = 256 ; using board_type = cell[MAX_SZ][MAX_SZ] ; struct move_type { int row = 0 ; int col = 0 ; } ; constexpr move_type INVALID_MOVE { -1, -1 } ; int num_available_moves( const board_type& board, int nrows, int ncols ) { int num_available = 0 ; for( int row = 0 ; row < nrows ; ++row ) for( int col = 0 ; col < ncols ; ++col ) num_available += int( board[row][col] == SPACE ) ; return num_available ; } move_type generate_random_move( const board_type& board, int nrows, int ncols ) { const int num_available = num_available_moves( board, nrows, ncols ) ; if( num_available > 0 ) { // pick a random move and return its row,col position int move_number = random_int( 1, num_available ) ; for( int row = 0 ; row < nrows ; ++row ) for( int col = 0 ; col < ncols ; ++col ) { if( board[row][col] == SPACE ) --move_number ; if( move_number == 0 ) return { row, col } ; } } return INVALID_MOVE ; // there are no valid moves left }``````
It's seems like I misdiscribe it, I mean to choose randomly one of the move I have listed, instead of always proritize the vertical one