generate-all-neigbors.cpp

class SudokuBoard {
    void generateAllNeighbors () {
        // generate row & col neighbors
        for (int n = 0; n < 9; ++n) {
            neighbors.insert({n, pos.j});
            neighbors.insert({pos.i, n});
        }

        auto iFloor = (pos.i / 3) * THIRD;
        auto jFloor = (pos.j / 3) * THIRD;

        // generate cell neighbors
        for (int n = iFloor; n < iFloor + 3; ++n) {
            for (int m = jFloor; m < jFloor + 3; ++m) {
                neighbors.insert({n, m});
            }
        }
    }
}