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Challenge 16: Reverse Parenthesis

curriculum/challenges/english/blocks/daily-coding-challenges-javascript/6821ebda237de8297eaee792.md

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--description--

Given a string that contains properly nested parentheses, return the decoded version of the string using the following rules:

  • All characters inside each pair of parentheses should be reversed.
  • Parentheses should be removed from the final result.
  • If parentheses are nested, the innermost pair should be reversed first, and then its result should be included in the reversal of the outer pair.
  • Assume all parentheses are evenly balanced and correctly nested.

--hints--

decode("(f(b(dc)e)a)") should return "abcdef".

js
assert.equal(decode("(f(b(dc)e)a)"), "abcdef");

decode("((is?)(a(t d)h)e(n y( uo)r)aC)") should return "Can you read this?".

js
assert.equal(decode("((is?)(a(t d)h)e(n y( uo)r)aC)"), "Can you read this?");

decode("f(Ce(re))o((e(aC)m)d)p") should return "freeCodeCamp".

js
assert.equal(decode("f(Ce(re))o((e(aC)m)d)p"), "freeCodeCamp");

--seed--

--seed-contents--

js
function decode(s) {

  return s;
}

--solutions--

js
function decode(s) {
  while (s.includes(')')) {
    const closeIndex = s.indexOf(')');
    const openIndex = s.lastIndexOf('(', closeIndex);
    const before = s.slice(0, openIndex);
    const group = s.slice(openIndex + 1, closeIndex).split('').reverse().join('');
    const after = s.slice(closeIndex + 1);
    s = before + group + after;
  }

  return s;
}