1. Implement a function to find the first non-repeating character in a string using a hash table.
2. Write a program to group anagrams from a list of strings using hashing.
3. Create a hash map that counts the frequency of elements in an array and returns the elements that appear more than a given threshold.
4. Implement a function to check if two strings are isomorphic using a hash map.
5. Write a program to find the longest substring without repeating characters using hashing.
6. Create a hash table to find the intersection of two arrays.
7. Implement a function to check if a string can be segmented into a space-separated sequence of one or more dictionary words using hashing.
8. Write a program to find all duplicates in an array using a hash map.
9. Create a hash map that returns the indices of the two numbers that add up to a specific target in an array.
10. Implement a function to find the longest palindromic substring using hashing.
11. Write a program to find all pairs in an array that sum to a specific value using a hash table.
12. Create a hash table to store pairs of words that are anagrams of each other from a given list.
13. Implement a function to find the minimum window substring that contains all characters of another string using hashing.
14. Write a program to check if a sequence of parentheses is valid using a hash table.
15. Create a hash map to count the frequency of characters in a string and return the top K frequent characters.
16. Implement a function to find the length of the longest consecutive sequence of numbers in an unsorted array using a hash set.
17. Write a program to find all unique quadruplets in an array that sum to a target value using hashing.
18. Create a hash table to find the longest substring with at most two distinct characters using hashing.
19. Implement a function to find the first repeating element in an array using a hash map.
20. Write a program to check if a string contains all unique characters using a hash set.
21. Create a hash map to store the count of distinct elements in each sliding window of size K in an array.
22. Implement a function to find all substrings of a string that are palindromes using a hash map.
23. Write a program to check if two strings are rotations of each other using hashing.
24. Create a hash table to store the frequency of elements in a matrix and find the most frequent element.
25. Implement a function to find the length of the longest substring with at most K distinct characters using hashing.
26. Write a program to find the longest subarray with equal number of 0s and 1s using hashing.
27. Create a hash map to find the longest consecutive sequence of characters in a string.
28. Implement a function to find all elements in an array that appear more than once and their counts using hashing.
29. Write a program to determine if a string can be formed by rearranging another string using a hash table.
30. Create a hash table to store pairs of indices of two strings that are anagrams of each other.
31. Implement a function to find all triplets in an array that sum to a specific value using hashing.
32. Write a program to find the maximum product of three integers in an array using a hash map.
33. Create a hash map that tracks the number of occurrences of each word in a paragraph.
34. Implement a function to determine if two strings are anagrams of each other, considering case sensitivity and spaces, using hashing.
35. Write a program to find the longest substring with no repeating characters that can be formed by removing at most one character using hashing.
36. Create a hash table to store mappings of students' IDs to their grades and find the student with the highest grade.
37. Implement a function to find the first unique word in a list of words using hashing.
38. Write a program to check if a string can be split into two substrings that are anagrams using hashing.
39. Create a hash map to store mappings of customer IDs to their purchase histories and analyze the most frequent items bought.
40. Implement a function to find the longest substring that contains only vowels using hashing.