1. Write a function to find the first non-repeating character in a string using hashing.
2. Implement a program to check if two strings are anagrams using a hash map.
3. Create a hash table to store user profiles and implement a function to retrieve a profile by user ID.
4. Write a program to count the frequency of each character in a given string using hashing.
5. Implement a function to find the longest substring without repeating characters using hashing.
6. Create a hash map to keep track of student IDs and their corresponding grades.
7. Write a program to find all pairs in an array that sum up to a specific target using hashing.
8. Implement a function to check if a list contains duplicates using a hash set.
9. Create a hash table to store product IDs and their prices and implement a function to get the price of a product.
10. Write a program to group anagrams from a list of strings using hashing.
11. Implement a function to find the longest consecutive sequence of numbers in an array using a hash map.
12. Create a hash map to store employee IDs and their corresponding department names.
13. Write a program to find the intersection of two arrays using hashing.
14. Implement a function to check if a string can be formed by rearranging another string using hashing.
15. Create a hash table to track the number of occurrences of words in a text document.
16. Write a program to find the smallest substring containing all characters of a given string using hashing.
17. Implement a function to find the number of unique elements in an array using a hash set.
18. Create a hash map to store the mapping of country names to their capitals.
19. Write a program to find the first repeating character in a string using hashing.
20. Implement a function to determine if two strings are permutations of each other using a hash map.
21. Create a hash table to keep track of book titles and their corresponding authors.
22. Write a program to find the longest substring with at most k distinct characters using hashing.
23. Implement a function to check if a string contains all unique characters using a hash set.
24. Create a hash map to track the number of votes for different candidates in an election.
25. Write a program to find the maximum occurring character in a string using hashing.
26. Implement a function to check if a string is a palindrome using a hash map.
27. Create a hash table to store the scores of different players in a game.
28. Write a program to find the longest prefix that is common among an array of strings using hashing.
29. Implement a function to determine if there are two numbers in an array that multiply to a specific target using hashing.
30. Create a hash map to track the number of items sold for different products.
31. Write a program to find the length of the longest substring with the same character occurring at least k times using hashing.
32. Implement a function to find all unique characters in a string using hashing.
33. Create a hash table to store the IDs and prices of products in an online store.
34. Write a program to find the most frequently occurring element in an array using hashing.
35. Implement a function to check if a given set of parentheses is valid using a hash set.
36. Create a hash map to track the number of times a character appears in a string.
37. Write a program to find the longest substring that contains only digits using hashing.
38. Implement a function to check if two strings are isomorphic using hashing.
39. Create a hash table to store timestamps and their corresponding event names.
40. Write a program to find all subsets of a set using hashing.