Find all duplicates in an array
November 20, 2022
array-and-hashmapProblem URL: Find all duplicates in an array
We will count the frequency of each number in the array, and return the numbers that appear twice.
class Solution:
def findDuplicates(self, nums: List[int]) -> List[int]:
freq = collections.Counter(nums)
return [num for num, count in freq.items() if count == 2]
Time complexity: O(n)
Space complexity: O(n)