Othello Challenge

#include <iostream>
#include <cmath>
using namespace std;
const int a=1,b=2,c=3,d=4,e=5,f=6,g=7,h=8,black=1,white=2,suggestion=10;
const string space = "\t  ";
//Othello challenge
//Copyright: Federico Rampazzo, 2011

int followLine(int grid[9][9], int i, int j, int vi, int vj,
               int color, int replace, bool target=true,
               int limit=0, int captured=0){

  //follow a line of color pieces using the vectors vi e vj starting from i,j
  //target==true: place a replace piece as soon as it founds a limit piece
  //target==false: place replace pieces along the line until it founds a limit piece
  //captured holds the number of captured pieces

  if (i>=1 && i<=8 && j>=1 && j<=8){
    if (grid[i][j]==color){
      int result = followLine(grid, i+vi, j+vj, vi, vj, color, replace, target, limit, captured+1);
      if (!target && result) grid[i][j] = replace;
      return result;
    }else if(grid[i][j]==limit && captured>0){
      if (target) grid[i][j] = replace;
      return 1;
    }else{
      return 0;
    }
  }
  return 0;
}

int showValidMoves(int grid[9][9], int color){ //display suggestions
  int opposite = ((color==black) ? white : black);
  int moves = 0;
  for (int i=1; i<=8; i++)
    for (int j=1; j<=8; j++)
      if (grid[i][j]==color)
        for (int k=-1; k<=1; k++)
          for (int h=-1; h<=1; h++)
            moves += followLine(grid, i+k, j+h, k, h, opposite, suggestion);
  return moves;
}

void cleanSuggestions(int grid[9][9]){ //clean the grid
  for (int i=1; i<=8; i++){
    for (int j=1; j<=8; j++){
      if (grid[i][j]==suggestion)
        grid[i][j] = 0;
    }
  }
}

int getWinner(int grid[9][9], int &blacks, int &whites){ //calculate the winner
  for (int i=1; i<=8; i++){
    for (int j=1; j<=8; j++){
      if (grid[i][j]==black)
        blacks++;
      else if (grid[i][j]==white)
        whites++;
    }
  }
  if (blacks>whites)
    return black;
  else if (blacks<whites)
    return white;
  else
    return 0;
}

void printGrid(int grid[9][9]){ //print the grid
  cout << space;
  cout << "  a b c d e f g h\n";
  for (int i=1; i<=8; i++){
    cout << space;
    cout << i << " ";
    for (int j=1; j<=8; j++){
      cout << ((grid[i][j]==white) ? "\u25CF" :
                ((grid[i][j]==black) ? "\u25CB" :
                  ((grid[i][j]==suggestion) ? "\u00B7" :
                  " "))) << " ";
    }
    cout << i << "\n";
  }
  cout << space;
  cout << "  a b c d e f g h\n";
}

int main(){
  int grid[9][9]={};

  grid[4][d] = grid[5][e] = white;
  grid[5][d] = grid[4][e] = black;
  int color = black; //black is first

  int consecutive = 0;
  bool legal = showValidMoves(grid, color)>0;

  while (legal || consecutive<2){ //2 stalls make the game end
    string player = ((color==black) ? "BLACK" : "WHITE");
    int opposite = ((color==black) ? white : black);

    printGrid(grid);

    if (!legal){
      consecutive++;
      cout << space << "No valid moves for " << player << "\n";
    }else{ //user input
      consecutive = 0;
      bool enteredMove = false;
      while (!enteredMove){
        cout << space << "It's " << player << "'s turn: ";
        string move; getline(cin, move);
        int i = (int) move[1]-48, j = (int) tolower(move[0])-96;
        if (grid[i][j]==suggestion){
          enteredMove = true;
          grid[i][j] = color;
          for (int k=-1; k<=1; k++)
            for (int h=-1; h<=1; h++)
              followLine(grid, i+k, j+h, k, h, opposite, color, false, color);
        }else{
          cout << space << "Unvalid move\n";
        }
      }
      cleanSuggestions(grid);
    }

    color = opposite;
    legal = showValidMoves(grid, color)>0;
  }
  //game over
  int blacks = 0, whites = 0;
  int winner = getWinner(grid, blacks, whites);
  cout << space;
  cout << ((winner==black) ? "BLACK" :
          ((winner==white) ? "WHITE" :
            "NOBODY")) << " wins! " <<
            blacks << "-" << whites << "\n";

}