哈希表卡片

dict的各种函数
dict.get(key,defaultvalue)

class Solution(object):
    def intersect(self, nums1, nums2):
        counts = {
    }
        res = []
        for num in nums1:
            counts[num] = counts.get(num, 0) + 1
        for num in nums2:
            if num in counts and counts[num] > 0:
                res.append(num)
                counts[num] -= 1
        return res

其他函数
enumerate遍历list的索引和值
zip同时遍历list或dict
e.g.:zip(dict1.values(),dict2.values())
s.find(x)找到数组s中值为x的索引，s.rfind(x)在数组中找到最后一个值为x的索引

class Solution:
    def findRestaurant(self, list1: List[str], list2: List[str]) -> List[str]:
        Aindex = {
    u: i for i, u in enumerate(list1)}
        best, ans = 1e9, []
        
        for j, v in enumerate(list2):
            i = Aindex.get(v, 1e9)
            if i + j < best:
                best = i + j
                ans = [v]
            elif i + j == best:
                ans.append(v)
        return ans