/* Assumes that board is not full and neither players has won.
 * Updates board with a random O move
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include<math.h>
#include <sys/types.h>
#include <time.h>


int K;  // KxK board

int main(int argc, char*argv[]){

  
  K = atoi(argv[1]);
  char* board = new char[K*K];
  memset(board, 0, K*K*sizeof(char));
  FILE* f = fopen("b.txt", "rt");
  int i = 0;
  while (!feof(f) && i < K*K){
    fscanf(f, "%c", &board[i]);
    i++;
  }
  fclose(f);
  time_t result = time(NULL);
  unsigned int seed = result;
  srand(seed);
  int move;
  do{
    move = (int) rint(rand() * 1.0 /RAND_MAX * (K*K - 1));
  }
  while (board[move]!='_');

  board[move] = 'O';
  
  f = fopen("b.txt", "wt");
  for(i = 0; i < K*K; i++)
    fprintf(f, "%c", board[i]);

  fclose(f);
  delete []board;
  
  exit(0);
}