HACKERRANK Cheat Sheet 2026

The 30 highest-yield HACKERRANK facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which keyword is used to inherit from a parent class in Python? → The parent class is passed in parentheses
2. What does `__name__ == '__main__'` check for in a Python module? → Whether the script is being run directly (not imported)
3. What is the output of the following code? ```python for i in range(10): if i % 2 == 0: continue if i > 6: break print(i) ``` → 1 3 5
4. Which of the following is a correct way to share your HackerRank Python certification with a potential employer? → Send a direct link to your public HackerRank profile or certificate URL
5. What is the Pythonic way to loop a fixed number of times without needing the loop variable? → for _ in range(n): ...
6. What is the output of this code? ```python x = 5 result = 'positive' if x > 0 else 'negative' if x < 0 else 'zero' print(result) ``` → positive
7. What is the result of: `Counter([1,1,2,3]) + Counter([1,2,2])`? → Counter({1: 3, 2: 3, 3: 1})
8. Which of the following scenarios would most likely result in a HackerRank certification being flagged or invalidated? → Using a second device to look up answers during the proctored exam
9. In Python, what does `collections.Counter([1,1,2,3,3,3])` return? → Counter({3: 3, 1: 2, 2: 1})
10. What should you do immediately after reading a HackerRank certification problem statement? → Analyze input/output format and constraints before coding
11. How do you define a custom exception class named `AppError` in Python? → class AppError(Exception):
12. What is the result of the following code? python words = ['py', 'thon', 'rocks'] print('-'.join(words)) → py-thon-rocks
13. What is the output of: ```python for x in range(1, 6, 2): print(x, end=' ') ``` → 1 3 5
14. What does the `*args` parameter allow in a Python function definition? → Accepting a variable number of positional arguments as a tuple
15. What will the following code print? ```python def add(a, b): return a + b result = add(b=3, a=7) print(result) ``` → 10
16. Which Python snippet uses dynamic programming to compute the nth Fibonacci number in O(n) time and O(1) space? → a,b=0,1 for _ in range(n): a,b=b,a+b return a
17. Given `with open('data.txt', 'w') as f: f.write('hello')`, what is the state of the file after the `with` block exits normally? → The file is closed and contains 'hello'
18. Which sorting algorithm has the best average-case and worst-case time complexity of O(n log n)? → Merge Sort
19. What is the result of `sorted([3,1,4,1,5], reverse=True)`? → [5, 4, 3, 1, 1]
20. In Python, what is the result of `[x for x in range(10) if x % 2 == 0]`? → [0, 2, 4, 6, 8]
21. What does `hash('hello')` return in Python? → An integer that may vary between runs
22. Which of the following correctly describes how HackerRank calculates a certification score? → Score = number of test cases passed / total test cases across all problems
23. Which of the following statements about the `collections.deque` object in Python is true? → It provides O(1) time complexity for append and pop operations from both ends.
24. What is a list comprehension in Python? → A concise syntax for creating lists by applying an expression to each item in an iterable
25. What is the most efficient way to count occurrences of elements in a Python list for HackerRank problems? → collections.Counter
26. Which of the following is a PRIMARY reason employers trust HackerRank Python certifications compared to self-reported skills on a resume? → The certification involves proctored, time-limited coding tasks
27. What makes the HackerRank Python Certification valuable in job applications? → It demonstrates verified Python skills.
28. Which of the following is a core topic in HackerRank's Python Basic exam related to error handling? → Using try/except blocks and raising exceptions
29. Which method moves the file pointer to a specific byte position within an open file? → seek()
30. How does holding a HackerRank Python certification typically affect a candidate's resume screening outcome? → It often helps bypass automated keyword filters and signals verified skill