private Iterable<int[]> adj(int i, int j) {
Bag<int[]> result = new Bag<>();
if (i > 0 && j > 0) {
result.add(new int[] {i - 1, j - 1});
}
if (i > 0) {
result.add(new int[] {i - 1, j});
}
if (i > 0 && j < N - 1) {
result.add(new int[] {i - 1, j + 1});
}
if (j > 0) {
result.add(new int[] {i, j - 1});
}
if (j < N - 1) {
result.add(new int[] {i, j + 1});
}
if (i < M - 1 && j > 0) {
result.add(new int[] {i + 1, j - 1});
}
if (i < M - 1) {
result.add(new int[] {i + 1, j});
}
if (i < M - 1 && j < N - 1) {
result.add(new int[] {i + 1, j + 1});
}
return result;
}
private void dfs(int i, int j) {
marked[i][j] = true;
if (wordTo[i][j].length() > 2 && dict.contains(wordTo[i][j])) {
wordsFromCell.add(wordTo[i][j]);
}
if (dict.keysWithPrefix(wordTo[i][j]).iterator().hasNext()) {
Iterable<int[]> adj = adj(i, j);
for (int[] a : adj) {
if (!marked[a[0]][a[1]]) {
String letter = board.getLetter(a[0], a[1]) + "";
if (Objects.equals(letter, "Q")) {
wordTo[a[0]][a[1]] = wordTo[i][j] + "QU";
} else {
wordTo[a[0]][a[1]] = wordTo[i][j] + letter;
}
dfs(a[0], a[1]);
}
}
}
marked[i][j] = false;
}