package tris

func (f Field) Lines() (int, Field) {
	full := [10]bool{true, true, true, true, true, true, true, true, true, true}
	empty := [10]bool{false, false, false, false, false, false, false, false, false, false}
	var n int
	var nf [][10]bool

	// count and collect
	for _, line := range f {
		if line == full {
			n++
		} else {
			nf = append(nf, line)
		}
	}

	// compress
	for i := 0; i < 20; i++ {
		if i < n {
			f[i] = empty
		} else {
			f[i] = nf[i-n]
		}
	}
	return n, f
}