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Tested Python solution for LeetCode 442 with 20 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 442 # by problem number
lcpy gen -s find_all_duplicates_in_an_array # by problem name
nums of length n where all the integers of nums are in the range [1, n] and each integer appears at most twice, return an array of all the integers that appears twice.
You must write an algorithm that runs in O(n) time and uses only constant auxiliary space, excluding the space needed to store the output
Input: nums = [4,3,2,7,8,2,3,1]
Output: [2,3]
Input: nums = [1,1,2]
Output: [1]
Input: nums = [1]
Output: []
n == nums.length1 <= n <= 10^51 <= nums[i] <= nnums appears once or twice.class Solution:
# Time: O(n)
# Space: O(1)
def find_duplicates(self, nums: list[int]) -> list[int]:
result: list[int] = []
for num in nums:
idx = abs(num) - 1
if nums[idx] < 0:
result.append(abs(num))
else:
nums[idx] = -nums[idx]
return result
| Time | Space |
|---|---|
| O(n) | O(1) |