1# Python 3+
2import collections
3collections.Counter(input_string)
4
5# Python 2 or custom results.
6{key: string.count(key) for key in set(string)}
7
8# Other ways are too slow. In the source, You can see the proves.
1count = {}
2for s in check_string:
3 if s in count:
4 count[s] += 1
5 else:
6 count[s] = 1
7
8for key in count:
9 if count[key] > 1:
10 print key, count[key]