Intersection of Two Arrays II in Python

Suppose we have two arrays A and B, there are few elements in these array. We have to find the intersection of them. So if A = [1, 4, 5, 3, 6], and B = [2, 3, 5, 7, 9], then intersection will be [3, 5]

To solve this, we will follow these steps −

• Take two arrays A and B
• if length of A is smaller than length of B, then swap them
• calculate the frequency of elements in the array and store them into m
• for each element e in B, if e is present in m, and frequency is non-zero,
  • decrease frequency m[e] by 1
  • insert e into the resultant array
• return the resultant array

Example

Let us see the following implementation to get better understanding −

 Live Demo

class Solution(object):
   def intersect(self, nums1, nums2):
      """
      :type nums1: List[int]
      :type nums2: List[int]
      :rtype: List[int]
      """
      m = {}
      if len(nums1)<len(nums2):
         nums1,nums2 = nums2,nums1
      for i in nums1:
         if i not in m:
            m[i] = 1
         else:
            m[i]+=1
      result = []
      for i in nums2:
         if i in m and m[i]:
            m[i]-=1
            result.append(i)
      return result
ob1 = Solution()
print(ob1.intersect([1,4,5,3,6], [2,3,5,7,9]))

Input

[1,4,5,3,6]
[2,3,5,7,9]

Output

[3,5]