codewars/go/kyu7/complementary_dna/k.go

package kata

func DNAStrand(dna string) string {
	s := make([]rune, len(dna))
	complements := map[rune]rune{'A':'T', 'T':'A', 'C':'G', 'G': 'C'}
	for i, r := range dna {
		s[i] = complements[r]
	}
	return string(s)
}