350. Intersection of Two Arrays II

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

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

Note:

• Each element in the result should appear as many times as it shows in both arrays.
• The result can be in any order.

Follow up:

• What if the given array is already sorted? How would you optimize your algorithm?
• What if nums1's size is small compared to nums2's size? Which algorithm is better?
• What if elements of nums2 are stored on disk, and the memory is limited such that you cannot load all elements into the memory at once?

class Solution(object):
    def intersect(self, nums1, nums2):
        """
        :type nums1: List[int]
        :type nums2: List[int]
        :rtype: List[int]
        """
        n1={}
        n2={}
        s=[]
        for i in nums1:
            n1[i]=n1.get(i,0)+1
        for i in nums2:
            n2[i]=n2.get(i,0)+1
        for k,v in n1.items():
            if k in n2.keys():
                for i in range(min(n1[k],n2[k])):
                    s.append(k)
        return s