langlib.js

module.exports = (() => {
  // each word must be a string
  function isClosedInSum (code, base = 2) {
    var i, j;
    var map = {};
    var nonClosedCouples = [];
    var missingElements = [];
    var missingMap = {};

    for (i=0; i<code.length; i++) {
      code[i] = code[i] + '';
      map[code[i]] = true;
    }

    for (i=0; i<code.length; i++) {
      for (j=i; j<code.length; j++) {
        if (!map[modSum(code[i], code[j], base)]) {
          nonClosedCouples.push([code[i], code[j]]);
          missingMap[modSum(code[i], code[j], base)] = true;
        }
      }
    }

    return {
      nonClosedCouples,
      missing: Object.keys(missingMap)
    };
  }

  // a and b are strings
  function modSum (as, bs, base = 2) {
    as = as + ''; bs = bs + '';
    var i;
    var sum = as.length > bs.length? as.split(''): bs.split('');

    for (i=0; i<Math.min(as.length, bs.length); i++) {
      sum[i] = (eval(as[i]) + eval(bs[i])) % base;
    }

    return sum.join('');
  }

  examples = {
    0: {
      code: [
        '0000000',
        '0011101',
        '0111010',
        '1110101',
        '1101001',
        '1010011',
        '0100111',
        '1001110'
      ],
      base: 2
    }, 1: {
      code: [
        '00000',
        '11001',
        '22002',
        '20210',
        '01211',
        '12212',
        '10120',
        '21121',
        '02122'
      ],
      base: 3
    }
  };

  return {
    isClosedInSum,
    modSum,
    examples
  };
})();