The Witness logic for handling for 3-color triple

test_stones_early_fail.c

Entity_Machine_Panel* panel;

bool shouldSolve = false;
Entity_Record_Player* recordPlayer = get_record_player(panel->entity_manager)
if (recordPlayer != NULL) {
  if (strings_match(panel->pattern_name, recordPlayer->lotus_onlyone_tricolor_solvable_name)) {
    shouldSolve = true;
  }
}
do {
  clear_dots(panel);
  make_n_by_n(panel, 5 /* n */, true /* connect_dots */, true /* should_add_finisher */);
  init_decorations(panel, 0x10 /* count */, 0 /* default_value */);
  panel->dot_flags[0] |= 0x02; // is_startpoint
  for (int i=5; i != 0; i--) {
    int slot = get_empty_decoration_slot(panel);
    panel->decorations[slot] = 0x102; // White stone
  }
  for (int i=2; i != 0; i--) {
    int slot = get_empty_decoration_slot(panel);
    panel->decorations[slot] = 0x104; // Purple stone
  }
  for (int i=2; i != 0; i--) {
    int slot = get_empty_decoration_slot(panel);
    panel->decorations[slot] = 0x105; // Green stone
  }
  panel->style_flags |= 0x100; // Has Stones
  if (test_stones_early_fail(panel)) continue;
  bool canSolve = is_solvable(panel);
} while (canSolve != shouldSolve);

bool test_stones_early_fail(Entity_Machine_Panel* panel) {
  int num_columns = panel->grid_size_x - 1
  int num_rows = panel->grid_size_y - 1
  if (panel->style_flags != 0x4000) { // Is Pillar
    num_columns++
  }
  if (num_columns <= 1 || num_rows <= 1) return false;

  for (int x = 0; x < num_columns; x++) {
    int idx = x;
    for (int y = 0; y < num_rows-1; y++ && idx += num_columns) {
      // Load 4 cells in a 2x2 pattern
      int cellA = panel->decorations[idx]
      if (cellA & 0x00000F00 != 0x100) { // Any Stone
        cellA = 0;
      }
      int cellB = panel->decorations[idx + 1];
      if (cellB & 0x00000F00 != 0x100) { // Any Stone
        cellB = 0;
      }
      int cellC = panel->decorations[idx + num_columns]
      if (cellC & 0x00000F00 != 0x100) { // Any Stone
        cellC = 0
      }
      int cellD = panel->decorations[idx + num_columns + 1]
      if (cellD & 0x00000F00 != 0x100) { // Any Stone
        cellD = 0
      }
      // First, check that a given pair of cells is non-empty.
      // Then, check if either of the two remaining cells is distinct from the two non-empty cells.
      // If both conditions pass, then there is an impossible L shape.
      if (cellA != 0 && cellB != 0 && cellA != cellB) {
        if (cellC != 0 && cellC != cellA && cellC != cellB) return true;
        if (cellD != 0 && cellD != cellA && cellD != cellB) return true;
      }
      if (cellB != 0 && cellC != 0 && cellB != cellC) {
        if (cellD != 0 && cellD != cellB && cellD != cellC) return true;
        if (cellA != 0 && cellA != cellB && cellA != cellC) return true;
      }
      if (cellC != 0 && cellD != 0 && cellC != cellD) {
        if (cellA != 0 && cellA != cellC && cellA != cellD) return true;
        if (cellB != 0 && cellB != cellC && cellB != cellD) return true;
      }
      if (cellD != 0 && cellA != 0 && cellD != cellA) {
        if (cellB != 0 && cellB != cellD && cellB != cellA) return true;
        if (cellC != 0 && cellC != cellD && cellC != cellA) return true;
      }
    }
  }

  return false;
}