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Balanced brackets

curriculum/challenges/english/blocks/rosetta-code-challenges/594dc6c729e5700999302b45.md

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--description--

Determine whether a generated string of brackets is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.

Examples:

InputOutput
<code>[]</code>true
<code>][</code>false
<code>[][]</code>true
<code>][]</code>false
<code>[]][[]</code>false
<code>[[[[]]]]</code>true

--before-each--

js
const testCases = [
  '[]',
  ']][[[][][][]][',
  '[][[[[][][[[]]]]]]',
  '][',
  '[[[]]]][[]',
  '][[]',
  '][[][]][[[]]',
  '[[][]]][',
  '[[[]]][[]]]][][[',
  '[]][[]]][[[[][]]',
  '][]][[][',
  '[[]][[][]]',
  '[[]]',
  ']][]][[]][[[',
  '][]][][[',
  '][][',
  '[]]]',
  ''
];

--hints--

isBalanced should be a function.

js
assert(typeof isBalanced === 'function');

isBalanced("[]") should return true.

js
assert(isBalanced(testCases[0]));

isBalanced("]][[[][][][]][") should return false.

js
assert(!isBalanced(testCases[1]));

isBalanced("[][[[[][][[[]]]]]]") should return true.

js
assert(isBalanced(testCases[2]));

isBalanced("][") should return false.

js
assert(!isBalanced(testCases[3]));

isBalanced("[[[]]]][[]") should return false.

js
assert(!isBalanced(testCases[4]));

isBalanced("][[]") should return false.

js
assert(!isBalanced(testCases[5]));

isBalanced("][[][]][[[]]") should return false.

js
assert(!isBalanced(testCases[6]));

isBalanced("[[][]]][") should return false.

js
assert(!isBalanced(testCases[7]));

isBalanced("[[[]]][[]]]][][[") should return false.

js
assert(!isBalanced(testCases[8]));

isBalanced("[]][[]]][[[[][]]") should return false.

js
assert(!isBalanced(testCases[9]));

isBalanced("][]][[][") should return false.

js
assert(!isBalanced(testCases[10]));

isBalanced("[[]][[][]]") should return true.

js
assert(isBalanced(testCases[11]));

isBalanced("[[]]") should return true.

js
assert(isBalanced(testCases[12]));

isBalanced("]][]][[]][[[") should return false.

js
assert(!isBalanced(testCases[13]));

isBalanced("][]][][[") should return false.

js
assert(!isBalanced(testCases[14]));

isBalanced("][][") should return false.

js
assert(!isBalanced(testCases[15]));

isBalanced("[]]]") should return false.

js
assert(!isBalanced(testCases[16]));

isBalanced("") should return true.

js
assert(isBalanced(testCases[17]));

--seed--

--seed-contents--

js
function isBalanced(str) {

  return true;
}

--solutions--

js
function isBalanced(str) {
  if (str === '') return true;
  let a = str;
  let b;
  do {
    b = a;
    a = a.replace(/\[\]/g, '');
  } while (a !== b);
  return !a;
}