The four bases found in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T).

In genetics, GC-content is the percentage of Guanine (G) and Cytosine (C) bases on a DNA molecule that are either guanine or cytosine. 

Given a DNA sequence (a string) return the GC-content in percent, rounded up to 2 decimal digits for Python, not rounded in all other languages.

For more information about GC-content you can take a look to [wikipedia GC-content](https://en.wikipedia.org/wiki/GC-content).

**For example**: the GC-content of the following DNA sequence is 50%:
"AAATTTCCCGGG".

**Note**: You can take a look to my others bio-info kata [here](http://www.codewars.com/users/nbeck/authored)

Source: codewars | Difficulty: EASY

Starter code: def gc_content(seq):
	

Solutions:
def gc_content(seq):
	if not seq:
		return 0.0
	else:
		res = seq.count('C') + seq.count('G')
		return round(res * 100 / len(seq), 2)


def gc_content(seq):
	if not seq:
		return 0
	gc_cnt = total_chars = 0
	for a in seq:
		if a in 'GC':
			gc_cnt += 1
		total_chars += 1
	return round(100.0 * gc_cnt / total_chars, 2)


def gc_content(seq):
	return round(sum((c in 'GC' for c in seq)) / len(seq) * 100, 2) if len(seq) else 0.0


def gc_content(seq):
	return bool(seq) and round(100 * (seq.count('C') + seq.count('G')) / len(seq), 2)


def gc_content(seq):
	try:
		result = (seq.count('G') + seq.count('C')) / len(seq) * 100
		result = round(result, 2)
		return result
	except ZeroDivisionError:
		return 0.0


from collections import Counter

def gc_content(seq):
	c = Counter(seq)
	return round((c['C'] + c['G']) / len(seq) * 100, 2) if seq else 0


def gc_content(seq):
	return round(100 * sum((x in 'GC' for x in seq)) / (len(seq) or 1), 2)