0.1 哈希

[1.两数之和](https://leetcode.cn/problems/two-sum/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        dic = {}
        for i, num in enumerate(nums):
            if target-num in dic:
                return [i, dic[target-num]]
            dic[num] = i
```
[49. 字母异位词分组](https://leetcode.cn/problems/group-anagrams/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        dic = {}
        for s in strs:
            sort_s = ''.join(sorted(s))
            if sort_s in dic:
                dic[sort_s].append(s)
            else:
                dic[sort_s] = [s]
        return list(dic.values())
```
[128. 最长连续序列](https://leetcode.cn/problems/longest-consecutive-sequence/submissions/516142135/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def longestConsecutive(self, nums: List[int]) -> int:
        ans = 0
        st = set(nums)
        for x in st:
            if x - 1 in st:
                continue
            y = x + 1
            while y in st:
                y += 1
            ans = max(ans,y-x)
        return ans
```