reverse-words.js

// Given a string and a set of delimiters, reverse the words in the string while maintaining
// the relative order of the delimiters. For example, given "hello/world:here", return "here/world:hello".
// Follow-up: Does your solution work for the following cases: "hello/world:here/", "hello//world:here"

const reverseWords = (string, delimiters) => {
  const aux = [];
  let word = '';
  // O(n)
  for (const str of string) {
    if (!delimiters.has(str)) {
      word += str;
      continue;
    }

    if (word.length) {
      aux.push(word);
      word = '';
    }
    aux.push(str);
  }

  if (word.length) {
    aux.push(word);
  }

  let start = 0;
  let end = aux.length - 1;

  // O(n)
  while (start !== end) {
    const a = aux[start];
    if (delimiters.has(a)) {
      start += 1;
      continue;
    }
    const b = aux[end];
    if (delimiters.has(b)) {
      end -= 1;
      continue;
    }
    [aux[start], aux[end]] = [aux[end], aux[start]];
    start += 1;
    end -= 1;
  }

  return aux.join('');
};
// [ 'hello', '/', 'world', ':', 'here' ]
//

[
  'hello/world:here',
  'hello/world:here/',
  'hello//world:here',
  ':hello/world:here',
].forEach((string) =>
  console.log(string, reverseWords(string, new Set(['/', ':'])))
);