1152. Analyze User Website Visit Pattern

class Solution:
    def mostVisitedPattern(self, username: List[str], timestamp: List[int], website: List[str]) -> List[str]:
        """ tc O(NlgN + N*(N-1)*(N-2)/3! )  sc O(N*(N-1)*(N-2)/3!)
        1. sort input by username and timestamp 
        2. put all the visited sites onto history list by username 
        3. for each history list, get its combination with size 3 to count the occurance of each sub sequesnce 
        4. get the lexically smallest subsequence with max occurance 
        
        knowledge to know: update a counter with list of keys using update(list_keys )
        """
        user_vs_web = collections.defaultdict(list)
        
        for _, user, web in sorted(zip(timestamp, username, website)):
            user_vs_web[user].append(web)
            
        cnt = collections.Counter()
        
        for each_list in user_vs_web.values():
            tmp_cnt = Counter(set(combinations(each_list,3))) # deduplicate  subsequence
            cnt += tmp_cnt
            #cnt.update(tmp_cnt)
        
        return list(min(cnt, key = lambda x :(-cnt[x], x)))
        #return list((max(sorted(cnt), key= cnt.get))) # put "dict" into sorted(), and only return keys