func parseCell(s string) Cell {
if len(s) != 5 {
return nil
}
if s == " " {
return &ValueCell{Val: bitset.Interval(1, 9)}
}
if s[2] == '\\' {
if v, h := parseClue(s[:2]), parseClue(s[3:]); v == errClue || h == errClue {
return nil
} else {
return &ClueCell{VClue: v, HClue: h}
}
}
e, err := strconv.Atoi(s)
if err != nil || e < 1 || 9 < e {
return nil
}
return &ValueCell{Val: bitset.Set(bitset.Element(e))}
}
func (b *block) check(cid cellId, v bitset.Element) bool {
sum := int(b.clue) - int(v)
used := bitset.Set(v)
b.cleft = b.cleft[:0]
for id, c := range b.cells {
if id != cid {
switch c.possible.Size() {
case 0:
return false
case 1:
e := c.possible.Min()
if used.Contains(e) {
return false
}
sum -= int(e)
used = used.Add(e)
default:
b.cleft = append(b.cleft, c)
}
}
}
return b.findFeas(0, sum, used)
}