Do not use the fact that there are only 3 moves left. The traditional minimax is fast and simpler to write.

Finally I decided to use your way and I got AC.
First of all, I cost tree leafs and then run minimax on the tree.
You did in the same way ?
On the leaf-costing I don't like how I find index for the child nodes. Is there a more beautiful way then in function below:

void costIt( char val=1, char pos = 2 ){
    char res = 0;
    for( char i = 0; i < 3; i++ ){
        if ( !arr[ f_x[ i ] ][ f_y[ i ] ] ){
            arr[ f_x[ i ] ][ f_y[ i ] ] = val;
            res = check();
            if ( res == 0 )
                costIt( val == 1 ? -1 : 1, pos*2+1 );
            else if ( !set[ pos > 10 ? (pos-1)/2 : pos ] ){
                cost[ pos > 10 ? (pos-1)/2 : pos  ] = res;
                set[ pos > 10 ? (pos-1)/2 : pos ] = true;
            }
            arr[ f_x[ i ] ][ f_y[ i ] ] = 0;
            pos++;
        }
    }
}

Edited by author 20.12.2011 10:24