freeCodeCamp/curriculum/challenges/spanish/08-coding-interview-prep/algorithms/no-repeats-please.spanish.md

id, title, localeTitle, challengeType

id	title	localeTitle	challengeType
a7bf700cd123b9a54eef01d5	No Repeats Please	No se repite por favor	5

Description

Devuelve el número de permutaciones totales de la cadena proporcionada que no tienen letras consecutivas repetidas. Supongamos que todos los caracteres de la cadena proporcionada son únicos. Por ejemplo, aab debería devolver 2 porque tiene 6 permutaciones totales ( aab , aab , aba , aba , baa , baa ), pero solo 2 de ellas ( aba y aba ) no tienen la misma letra (en este caso, a ) repitiendo. Recuerda usar Read-Search-Ask si te atascas. Trate de emparejar el programa. Escribe tu propio código.

Instructions

Tests

tests:
  - text: <code>permAlone(&quot;aab&quot;)</code> debe devolver un número.
    testString: 'assert.isNumber(permAlone("aab"), "<code>permAlone("aab")</code> should return a number.");'
  - text: <code>permAlone(&quot;aab&quot;)</code> debe devolver 2.
    testString: 'assert.strictEqual(permAlone("aab"), 2, "<code>permAlone("aab")</code> should return 2.");'
  - text: <code>permAlone(&quot;aaa&quot;)</code> debe devolver 0.
    testString: 'assert.strictEqual(permAlone("aaa"), 0, "<code>permAlone("aaa")</code> should return 0.");'
  - text: <code>permAlone(&quot;aabb&quot;)</code> debe devolver 8.
    testString: 'assert.strictEqual(permAlone("aabb"), 8, "<code>permAlone("aabb")</code> should return 8.");'
  - text: <code>permAlone(&quot;abcdefa&quot;)</code> debe devolver 3600.
    testString: 'assert.strictEqual(permAlone("abcdefa"), 3600, "<code>permAlone("abcdefa")</code> should return 3600.");'
  - text: <code>permAlone(&quot;abfdefa&quot;)</code> debe devolver 2640.
    testString: 'assert.strictEqual(permAlone("abfdefa"), 2640, "<code>permAlone("abfdefa")</code> should return 2640.");'
  - text: <code>permAlone(&quot;zzzzzzzz&quot;)</code> debe devolver 0.
    testString: 'assert.strictEqual(permAlone("zzzzzzzz"), 0, "<code>permAlone("zzzzzzzz")</code> should return 0.");'
  - text: <code>permAlone(&quot;a&quot;)</code> debe devolver 1.
    testString: 'assert.strictEqual(permAlone("a"), 1, "<code>permAlone("a")</code> should return 1.");'
  - text: <code>permAlone(&quot;aaab&quot;)</code> debe devolver 0.
    testString: 'assert.strictEqual(permAlone("aaab"), 0, "<code>permAlone("aaab")</code> should return 0.");'
  - text: <code>permAlone(&quot;aaabb&quot;)</code> debe devolver 12.
    testString: 'assert.strictEqual(permAlone("aaabb"), 12, "<code>permAlone("aaabb")</code> should return 12.");'

Challenge Seed

function permAlone(str) {
  return str;
}

permAlone('aab');

Solution

function permAlone(str) {
  return permutor(str).filter(function(perm) {
    return !perm.match(/(.)\1/g);
  }).length;
}

function permutor(str) {
  // http://staff.roguecc.edu/JMiller/JavaScript/permute.html
  //permArr: Global array which holds the list of permutations
  //usedChars: Global utility array which holds a list of "currently-in-use" characters
  var permArr = [], usedChars = [];
  function permute(input) {
    //convert input into a char array (one element for each character)
    var i, ch, chars = input.split("");
    for (i = 0; i < chars.length; i++) {
      //get and remove character at index "i" from char array
      ch = chars.splice(i, 1);
      //add removed character to the end of used characters
      usedChars.push(ch);
      //when there are no more characters left in char array to add, add used chars to list of permutations
      if (chars.length === 0) permArr[permArr.length] = usedChars.join("");
      //send characters (minus the removed one from above) from char array to be permuted
      permute(chars.join(""));
      //add removed character back into char array in original position
      chars.splice(i, 0, ch);
      //remove the last character used off the end of used characters array
      usedChars.pop();
    }
  }
  permute(str);
  return permArr;
}

permAlone('aab');