[ppxyn1] WEEK 01 solutions

[ppxyn1]

답안 제출 문제

• Contains Duplicate
• Two Sum
• Top K Frequent Elements
• Longest Consecutive Sequence
• House Robber

작성자 체크 리스트

• Projects의 오른쪽 버튼(▼)을 눌러 확장한 뒤, Week를 현재 주차로 설정해주세요.
• 문제를 모두 푸시면 프로젝트에서 Status를 In Review로 설정해주세요.
• 코드 검토자 1분 이상으로부터 승인을 받으셨다면 PR을 병합해주세요.

검토자 체크 리스트

Important

본인 답안 제출 뿐만 아니라 다른 분 PR 하나 이상을 반드시 검토를 해주셔야 합니다!

• 바로 이전에 올라온 PR에 본인을 코드 리뷰어로 추가해주세요.
• 본인이 검토해야하는 PR의 답안 코드에 피드백을 주세요.
• 토요일 전까지 PR을 병합할 수 있도록 승인해주세요.

[daiyongg-kim]

코멘트 참고하세요.

[daiyongg-kim]

You must write an algorithm that runs in O(n) time.

• 제약사항이 있습니다.
• sorting 사용하면 nlog(n) 이라 성공하더라도 맞지 않는 것 같습니다.

[ppxyn1]

@DaleStudy

[dalestudy]

Great job on implementing a variety of solutions across different problems! Your code is generally clear and follows good practices. Here are some constructive suggestions to enhance your solutions further:

1. Time/Space Complexity Annotations: Adding comments like # TC: O(n), SC: O(n) will help clarify the efficiency of your approaches, especially for larger inputs.

2. Contains Duplicate: Your hash-based method is efficient. To improve readability, you could use if nums[i] in count_dict: directly without keys() since in checks keys by default. Also, consider using a set for even cleaner code: return len(set(nums)) < len(nums).

3. Longest Consecutive Sequence: Your Hash approach is optimal. The commented sorting method is less efficient (O(n log n)) but worth noting. Your current implementation correctly achieves O(n) time.

4. Top K Frequent Elements: Using sorted() is fine, but for large datasets, Python's collections.Counter with most_common() can be more concise and potentially faster.

5. Two Sum: Your current solution works but has O(n^2) complexity due to in and index() on slices. A more optimal approach is using a dictionary to store visited numbers and their indices, achieving O(n).

6. House Robber: Your DP implementation is clear and efficient. For readability, consider adding comments explaining the DP relation: max loot up to house i.

7. Code Style: Always include necessary imports at the top (e.g., from typing import List) for completeness. Consistent indentation and spacing improve readability.

Overall, you're on the right track! Incorporating these suggestions will make your solutions more efficient and easier to understand. Keep up the excellent work!

[daiyongg-kim]

수고하셨스니다.