题目：

我的解法：

1 def checkio(text): 2     import string 3     str = text.encode().lower() 4     adict = {} 5     for i in  string.lowercase[::-1]: 6         if (str.count(i) > 0 ): 7             adict[i] = str.count(i) 8     tmp = max(adict.values()) 9     tmpch = 'z'10     for x in adict:11         if tmp == adict[x]:12             print x13             if tmpch > x:14                 print x15                 tmpch = x16     return tmpch

 

感觉还不错的解法：

1 def checkio(s):2     s = s.lower()3     l = list(set((x,s.count(x)) for x in s if x.islower()))4     l.sort(key = lambda x: (-x[1],x[0]))5     return l[0][0]