349. Intersection of Two Arrays

Given two arrays, write a function to compute their intersection.

Example:
Given nums1 = ​​[1, 2, 2, 1]​​, nums2 = ​​[2, 2]​​​, return ​​[2]​​.

Note:

• Each element in the result must be unique.
• The result can be in any order.

class Solution(object):
    def intersection(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: List[int]
        """

        small = []
        big = []
        if len(nums1) < len(nums2):
            small = nums1
            big = nums2
        else:
            small = nums2
            big = nums1

        r = []
        for i in small:
            if i in big and i not in r:
                r.append(i)
        return

虽然AC了，但是用时太长了，需要优化一下

优化的思路是使用set，去重

class Solution(object):
    def intersection(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: List[int]
        """
        s = set(nums2)# 去重
        b = set(nums1)

        r = []
        for i in s:
            if i in b and i not in r:
                r.append(i)
                b.remove(i)    
        return