Find the Isogram

README.md

Write a program that checks if a word supplied as the argument is an Isogram. An Isogram is a word in which no letter occurs more than once. Create a function called is_isogram that takes one argument, a word to test if it's an isogram. This method should return a tuple/list/array of the word and a boolean indicating whether it is an isogram. If the argument supplied is an empty string, return the argument and False, ie (argument, False). If the argument supplied is not a string, raise a TypeError with the message 'Argument should be a string'. The challenge here is to write three unique solutions, using whichever language you like. However, you must maintain the specified identifiers and error messages in the question and use the least possible number of characters to solve the problem. White space will be ignored for readability's sake.

is_isogram.py

#using dictionaries
#191
def is_isogram(w):
    if type(w) != str:
        raise TypeError('Argument should be a string')
    if not w:
        return w, False
    c = [k for k in w]
    d = {}
    for i in range(len(c)):
        if c[i] in d:
            return w, False
        else:
            d[c[i]] = ''
    return w, True

#using lists
#207
def is_isogram(w):
    if type(w) != str:
        raise TypeError('Argument should be a string')
    if not w:
        return w, False
    s = []
    c = [c for c in w]
    for i in range(len(c)):
        if c[i] in s:
            return (w, False)
        elif c[i] not in s:
            s.append(c[i])
    return w, True

#using sets
#148
def is_isogram(w):
    if type(w) != str:
        raise TypeError('Argument should be a string')
    s = set(c for c in w)
    if not w or len(w) != len(s):
        return w, False
    else:
        return w, True

Using Array in JavaScript: 162 chars

is_isogram = (w) => {
	if (typeof(w) != "string") throw new Error("Argument should be a string");
	return [w, w.split('').reduce((a, b) => a.indexOf(b) < 0 ? a.concat(b) : a, []).length == w.length];
}

Using object/dict in JavaScript: 161 chars

is_isogram = (w) => {
	if (typeof(w) != "string") throw new Error("Argument should be a string");
	return [w, Object.keys(w.split('').reduce((a, b) => { a[b] = true; return a }, {})).join('') == w];
}

Using Set in JavaScript: 156 chars

is_isogram = (w) => {
	if (typeof(w) != "string") throw new Error("Argument should be a string");
	return [w, w.split('').reduce((a, b) => { a.add(b); return a }, new Set()).size == w.length];
}

In c#, using Dictionary ... 217 chars

Tuple<string, bool> isIsogram(string word) {
	return new Tuple<string, bool>(word, word.ToCharArray().Aggregate(new Dictionary<char, bool>(), (a, b) => {
		if (!a.ContainsKey(b)) a.Add(b, true);
		return a;
	}).Count() == word.Length);
}

Using Set with JS:

function isIsogram (str) {
  const cut = str.replace('-', '')
  return new Set(cut).size === cut.length
}

Or either using bit mask with JS:

function isIsogram (str) {
  let bs = 0b0
  for (let i = 0; i < str.length; i += 1) {
    const idx = str.charCodeAt(i) - 97
    if ((bs & (1 << idx)) === 0) {
      bs |= 1 << idx
    }
    else {
      return false
    }
  }
  return true
}