leetcode 349. Intersection of Two Arrays ( Python )

描述

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

Example 1:

Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]

Example 2:

Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [9,4]

Note:

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

解析

根据题意，就是找出交集列表，时间复杂度 O(N+M)，O(N) 用于 nums1 转换成 set , O(M) 用于 nums2 转换成 set ,空间复杂度最多为 O(N+M)。

解答

class Solution(object):
    def intersection(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: List[int]
        """
        set1 = set(nums1)
        set2 = set(nums2)
        if len(set1) < len(set2):
            return self.set_intersection(set1,set2)
        else:
            return self.set_intersection(set2,set1)
        
        
    def set_intersection(self, nums1, nums2):
        return [x for x in nums1 if x in nums2]                     

运行结果

Runtime: 32 ms, faster than 78.84% of Python online submissions for Intersection of Two Arrays.
Memory Usage: 11.9 MB, less than 46.09% of Python online submissions for Intersection of Two Arrays.
	

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