哈希表242|349|202|1

242有效的字母异位词

class Solution:
    def isAnagram(self, s: str, t: str) -> bool:
        record = [0] * 26
        for i in s:
            index = ord(i) - ord('a')
            record[index] += 1
        for i in t:
            index = ord(i) - ord('a')
            record[index] -= 1
        for i in record:
            if i != 0:
                return False
        return True

349两个数组的交集

class Solution:
    def intersection(self, nums1: List[int], nums2: List[int]) -> List[int]:
        set1 = set(nums1)
        set2 = set(nums2)
        return list(set1 & set2)

202快乐数

class Solution:
    def isHappy(self, n: int) -> bool:
        ifExist = set()
        while n != 1:
            result = self.calSum(n)
            if result in ifExist:
                return False
            else:
                ifExist.add(result)
                n = result
        return True
    def calSum(self, n: int) -> int:
        result = 0
        for i in str(n):
            result += int(i) ** 2
        return result

1两数之和

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        my_dict = {}
        result = []
        for i in range(len(nums)):
            if (target - nums[i]) in my_dict:
                result.append(i)
                result.append(my_dict[target - nums[i]])
                return result
            else:
                my_dict[nums[i]] = i
        return result