Find Second Largest

Return the second largest unique element from a list of numbers.

sorting max unique list

Write a function `second_largest(nums)` that takes a list of integers (or floats) `nums` and returns the **second largest distinct value**. If the list has fewer than two distinct values, return `None`.

- Only unique values are considered (e.g., for `[5, 5, 3]`, the distinct values are 5 and 3, so the second largest is 3).
- The input list may be empty.
- The input may contain negative numbers.
- Do not modify the original list.

Your task: implement the function exactly as specified.

Constraints

- `0 <= len(nums) <= 10^5`
- Values are integers or floats within typical Python range.
- Time complexity should be O(n log n) or better (e.g., O(n) is preferred).

Example

['>>> second_largest([1, 2, 3])', '2', '>>> second_largest([3, 3, 3])', 'None', '>>> second_largest([5, 5, 4, 4, 3, 2])', '4', '>>> second_largest([])', 'None']

10 points ~10 min

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Hints

Use `set()` to remove duplicates.

If the set has fewer than 2 elements, return None.

Sort the set or use two passes to find max and second max.

For O(n) time, track the two largest values in one pass.

Test Results

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