Given two arrays, write a function to compute their intersection.
Example 1:
Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2,2]
Example 2:
Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [4,9]
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?
Solution in python:
class Solution:
def intersect(self, nums1: List[int], nums2: List[int]) -> List[int]:
adic = {}
bdic = {}
result = []
for item in nums1:
if item not in adic.keys():
adic[item] = 1
else:
adic[item] += 1
for item in nums2:
if item not in bdic.keys():
bdic[item] = 1
else:
bdic[item] += 1
for key in bdic.keys():
if key in adic.keys():
count = min(adic[key], bdic[key])
while count > 0:
result.append(key)
count -= 1
return result
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