board.cpp

#include "board.h"

#include <fstream>
#include <vector>

// We cash the neighbors of a tile to save time while scoring a board
// These represent the 8 neighbors of a tile or grid position
// up, down, left, right and the four diagonals
int row_inc[8] = {-1, -1, -1, 0, 1, 1, 1, 0};
int col_inc[8] = {-1, 0, 1, 1, 1, 0, -1, -1};

// neighbor cache
int **neighbors;

// for any tile get it's neighbors
// start with the 8 grid neighbors and then filter out any tiles
// that are out of the grid
int get_neighbor(int tile, int neighbor) {
  int row = (tile / GRID_SIZE) + row_inc[neighbor];
  int col = (tile % GRID_SIZE) + col_inc[neighbor];
  if (row < 0 || row >= GRID_SIZE || col < 0 || col >= GRID_SIZE) return -1;
  return (row * GRID_SIZE) + col;
}

// build the neighbor cache
void build_neighbors() {
  neighbors = new int *[BOARD_SIZE];
  for (int i = 0; i < BOARD_SIZE; i++) {
    neighbors[i] = new int[9];
    std::fill_n(neighbors[i], 9, -1);

    int num_neighbors = 0;
    for (int j = 0; j < 8; j++) {
      int neighbor = get_neighbor(i, j);

      if (neighbor != -1) {
        neighbors[i][num_neighbors] = get_neighbor(i, j);
        num_neighbors++;
      }
    }
  }
}

void print_neighbors() {
  for (int i = 0; i < BOARD_SIZE; i++) {
    for (int j = 0; j < 9; j++) cout << neighbors[i][j] << ' ';
    cout << endl;
  }
}

vector<Board> input_boards;
bool read_boards(char *board_file) {
  string board;
  fstream board_stream(board_file);
  if (!board_stream) {
    cerr << "no dictionary file" << endl;
    return false;
  }
  while (getline(board_stream, board)) {
    input_boards.push_back(board);
  }
  return true;
}