Core Python — Basic (50+ Coding Exercises)

1. Write a program that reads two integers and prints their sum, difference, product, and quotient (handle division by zero).
2. Write a program that reads a string and prints it reversed.
3. Write a program that checks whether a number is even or odd.
4. Write a program that finds the maximum of three numbers.
5. Write a program that computes the factorial of (n) (iterative).
6. Write a program that prints the first (n) Fibonacci numbers.
7. Write a program that checks if a number is prime.
8. Write a program that prints all primes up to (n).
9. Write a program that counts vowels in a string.
10. Write a program that checks if a string is a palindrome (ignore spaces).
11. Write a program that sums all numbers in a list.
12. Write a program that finds the second-largest number in a list.
13. Write a program that removes duplicates from a list (preserve order).
14. Write a program that merges two lists and sorts the result.
15. Write a program that counts occurrences of each word in a sentence.
16. Write a program that finds the most frequent character in a string.
17. Write a program that converts Celsius to Fahrenheit and vice versa.
18. Write a program that computes simple interest and compound interest.
19. Write a program that prints a right triangle pattern of * of height (n).
20. Write a program that prints a multiplication table for a given number up to 10.
21. Write a program that computes the sum of digits of an integer.
22. Write a program that computes the digital root of a number.
23. Write a program that checks whether two strings are anagrams.
24. Write a program that splits a list into chunks of size (k).
25. Write a program that rotates a list right by (k).
26. Write a program that finds common elements between two lists (unique output).
27. Write a program that finds intersection and union of two sets.
28. Write a program that safely reads an integer from input until valid.
29. Write a program that uses a dict as a phonebook (add/search/delete).
30. Write a program that sorts a dictionary by values.
31. Write a program that counts how many times each letter appears (a–z only).
32. Write a program that removes punctuation from a string.
33. Write a program that replaces multiple spaces with a single space.
34. Write a program that finds the longest word in a sentence.
35. Write a program that generates a list of squares from 1 to (n).
36. Write a program that filters out negative numbers from a list.
37. Write a program that reads a file and counts the number of lines, words, and characters.
38. Write a program that copies a text file to another file.
39. Write a program that appends a new line to a file.
40. Write a program that reads a CSV-like file (comma-separated) and prints each row as a list.
41. Write a function is_leap_year(year) and test it with multiple inputs.
42. Write a function gcd(a, b) using Euclid’s algorithm.
43. Write a function lcm(a, b) using gcd.
44. Write a function that returns (min, max) from a list (without using built-ins min/max).
45. Write a function that flattens a 2D list into 1D.
46. Write a function that counts how many times a substring appears in a string (overlapping allowed).
47. Write a function that validates a password (min length, digit, uppercase, lowercase).
48. Write a program that simulates a basic calculator loop until user types quit.
49. Write a program that converts an integer to binary (without using bin()).
50. Write a program that converts a binary string to integer (without using int(x, 2)).
51. Write a program that finds the first non-repeating character in a string.
52. Write a program that checks if a list is sorted (ascending).