Python Coding Challenge: Two People with the Same Birthday

See Python: Tips and Tricks for similar articles.
Looking to improve your Python skills? Check out Webucator’s Python classes.

Python Coding Challenge: You’re in New York City. You walk up to a stranger and ask her what her birthday is. If her birthday is the same as yours, you win. If not, you take her hand and the two of you walk up to another stranger and ask him his birthday. If his birthday is the same as either of yours, you win. If not, one of you takes his hand, and you walk up to another stranger… Keep going until you find someone who has the same birthday as someone else in your group. Use Python to figure out how many tries it will take you.

Give it a try and then check out the possible solution below the image: Holding Hands

One Possible Solution

import random
attempts = []
for i in range(10000):
    bd = random.randint(1,366)
    bds = [bd]
    while True:
        bd = random.randint(1,366)
        if bd not in bds:
            bds.append(bd)
        else:
            break
    attempts.append(len(bds))
sum(attempts) / len(attempts), max(attempts)

For me, this output: 23.7019, 77

So, on average, it should take 23 to 24 tries to find someone. Now go give it a try for real and see if that’s right.

Written by Nat Dunn.


Related Articles

  1. Scientific Notation in Python
  2. Understanding Python’s __main__ variable
  3. Associate Python Files with IDLE
  4. Python: isdigit() vs. isdecimal()
  5. Python Color Constants Module
  6. Python: pow(x, y, z) less efficient than x**y % z
  7. A Python Model for Ping Pong Matches
  8. Bulk Convert Python files to IPython Notebook Files (py to ipynb conversion)
  9. Collatz Conjecture in Python
  10. Finally, a use case for finally – Python Exception Handling
  11. Python Clocks Explained
  12. Python’s date.strftime() slower than str(), split, unpack, and concatenate?
  13. Bi-directional Dictionary in Python
  14. Maximum recursion depth exceeded while calling a Python object
  15. Basic Python Programming Exercise: A Penny Doubled Every Day
  16. Creating an Email Decorator with Python and AWS
  17. How to Create a Simple Simulation in Python – Numeric Data
  18. Python Coding Challenge: Two People with the Same Birthday (this article)
  19. How to find all your Python installations on Windows
  20. Change Default autosave Interval in JupyterLab
  21. Interactive Quiz using IPython Notebook
  22. When to use Static Methods in Python? Never
  23. Converting Leading Tabs to Spaces with Python
  24. Simple Python Script for Extracting Text from an SRT File
  25. Python Virtual Environments with venv
  26. Mapping python to Python 3 on Your Mac
  27. How to Make IDLE the Default Editor for Python Files on Windows
  28. How to Do Ternary Operator Assignment in Python
  29. How to Convert Seconds to Years with Python
  30. How to Create a Python Package
  31. How to Read a File with Python
  32. How to Check the Operating System with Python
  33. How to Use enumerate() to Print a Numbered List in Python
  34. How to Repeatedly Append to a String in Python
  35. Checking your Sitemap for Broken Links with Python
  36. How to do Simultaneous Assignment in Python
  37. Visual Studio Code - Opening Files with Python open()
  38. How to Slice Strings in Python
  39. How Python Finds Imported Modules
  40. How to Merge Dictionaries in Python
  41. How to Index Strings in Python
  42. How to Create a Tuple in Python