· Sep 19, 2022

[Coding Challenge] Complementary DNA

Hello community,


Yesterday was celebrated the "World Medical Ethics Day" https://www.ama.com.au/media/wma-medical-ethics-day


We could celebrate it with a programming quiz or challenge:


Deoxyribonucleic acid (DNA) is a chemical found in the nucleus of cells and carries the "instructions" for the development and functioning of living organisms.

If you want to know more: http://en.wikipedia.org/wiki/DNA

In DNA strings, symbols "A" and "T" are complements of each other, as "C" and "G". Your function receives one side of the DNA (string, except for Haskell); you need to return the other complementary side. DNA strand is never empty or there is no DNA at all (again, except for Haskell).

More similar exercise are found here: http://rosalind.info/problems/list-view/ (source)

Example: (input --> output)

"GTAT" --> "CATA"

Satement extracted from: https://www.codewars.com/kata/554e4a2f232cdd87d9000038/java


Test cases:

import org.junit.Test;
import static org.junit.Assert.assertEquals;
import org.junit.runners.JUnit4;

public class DnaStrandTest {
    public void test01() {
       assertEquals("TTTT", DnaStrand.makeComplement("AAAA"));
    public void test02() {
       assertEquals("TAACG", DnaStrand.makeComplement("ATTGC"));
    public void test03() {
       assertEquals("CATA", DnaStrand.makeComplement("GTAT"));
    public void test04() {
       assertEquals("TTCC", DnaStrand.makeComplement("AAGG"));
    public void test05() {
       assertEquals("GCGC", DnaStrand.makeComplement("CGCG"));
    public void test06() {
       assertEquals("TAACG", DnaStrand.makeComplement("ATTGC"));
    public void test07() {



🌐🕸📔 Would you be able to code a solution for this?

Discussion (5)2
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As a reference a the Java solution:

Could be:

import java.util.*;

public class DnaStrand {

  static final Map<String,String> letters = Map.ofEntries(Map.entry("A","T"),Map.entry("T","A"),Map.entry("G","C"),Map.entry("C","G"));

  public static String makeComplement /*🧬🔁🧬*/ (String dna) {
    StringBuilder result = new StringBuilder();
    for(String letter:dna.split("")){
    return result.toString();

Would you like to improve this in ObjectScript?

Are you able?

Great spot @Timothy Leavitt 

Extra syntax sugar, can project as method expression to make more transparently embedded.

 ClassMethod makeComplement(As %String) As %String [CodeMode = expression]

Also I believe Java lacks convenience of compile time ObjectScript macros:

#define DNAComplement(%dna) $tr(%dna,"ATGC","TACG")

Write $$$DNAComplement("ATC")