Codewars - Two to One

Salutations.

I'm posting Codewars challenges and my thought process in this series. I'm using JS and Node 18 whenever possible. Just for the sake of clarity, I'm making fair use of them.

Ok, this was juicy. In essence, you have to remove duplicates in a string, order what's left and join two strings. Not exactly in that order. Actually, I did it in the exact opposite way. And I also built an utility function for a very specific step (removing duplicates).

---

First, concatenate two strings. Easy:

let longest = s1 + s2;

---

Second, split up the letters:

let array = new Array(s1.length + s2.length);
for (let i = 0 ; i < s1.length + s2.length ; i++ ){
    array[i] = longest[i];
  }

---

Third, sort the letters:

array = array.sort((a, b) => a.localeCompare(b));
// (a, b) => a.localeCompare(b)  THIS IS REDUNDANT, but I leave it as a reminder

---

Fourth, remove duplicates:

function keepFirstLetter(array){
  let arrayFixed = new Array(array.length);
  let counter = 0;
  arrayFixed[0] = array[0];


  for (let i = 0 ; i < array.length ; i++ ){
    if (arrayFixed[counter] != array[i]){
      counter++;
      arrayFixed[counter] = array[i];
    }
  }

  return arrayFixed;
}

---

Fifth, clean up:

array = array.join("");

---

Last, place every piece of the puzzle together:

function longest(s1, s2) {
  let array = new Array(s1.length + s2.length);

  let longest = s1 + s2;

  for (let i = 0 ; i < s1.length + s2.length ; i++ ){
    array[i] = longest[i];
  }

  array = array.sort((a, b) => a.localeCompare(b));

  array = keepFirstLetter(array);

  array = array.join("")

  return array;
}

function keepFirstLetter(array){
  let arrayFixed = new Array(array.length);
  let counter = 0;
  arrayFixed[0] = array[0];

  for (let i = 0 ; i < array.length ; i++ ){
    if (arrayFixed[counter] != array[i]){
      counter++;
      arrayFixed[counter] = array[i];
    }
  }

  return arrayFixed;
}

It's definitely NOT performant. I don't like that second loop. And it's not so clean either. Someday I'll need to revisit this one.

Be well. Drink water 💧💧💧.

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Comments

[Alex Mustiere]

I propose a more simple approach for this "problem":

const towToOne = (s1, s2) => {
  // concatenate and transform to array
  const concat = (s1 + s2).split('');

  // remove duplicates
  const cleanConcat = [...new Set(concat)];

  // sort
  const sortedConcat = cleanConcat.sort((a, b) => a.localeCompare(b));

  // return as string
  return sortedConcat.join('');
};

const [s1, s2] = ['dbacfe', 'cdgdchid'];
const result = towToOne(s1, s2);
console.log(`towToOne('${s1}', '${s2}') is '${result}'`);

You can simplify the twoToOne function if you want:

const towToOne = (s1, s2) => {
  return [...new Set((s1 + s2).split(''))].sort((a, b) => a.localeCompare(b)).join('');
};