LeetCode Top Interview 150 - Hashmap

In this chapter, there are several problems that are rather straightforward and possess numerous approaches. As a result, those questions have been omitted herein.

Group Anagrams 

Group Anagramshttps://leetcode.cn/problems/group-anagrams/

Difficulty: MED

class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        anagrams = {}
        for s in strs:
            iden = "".join(sorted(s))
            if iden in anagrams:
                anagrams[iden].append(s)
            else:
                anagrams[iden] = [s]
        return list(anagrams.values())

 Longest Consecutive Sequence

Longest Consecutive Sequencehttps://leetcode.cn/problems/longest-consecutive-sequence/Difficulty: MED

class Solution:
    def longestConsecutive(self, nums: List[int]) -> int:
        # searching in set O(1)
        # searching in list O(n)
        res = 0
        set_nums = set(nums)
        for num in set_nums:
            if num - 1 not in set_nums:
                start = num
                while num in set_nums:
                    num += 1
                res = max(res, num - start)
        return res