Topic: Hashing-question / Level: Advanced

• 401. Implement a function to find the first non-repeating character in a string using a hash table.
• 402. Write a program to group anagrams from a list of strings using hashing.
• 403. Create a hash map that counts the frequency of elements in an array and returns the elements that appear more than a given threshold.
• 404. Implement a function to check if two strings are isomorphic using a hash map.
• 405. Write a program to find the longest substring without repeating characters using hashing.
• 406. Create a hash table to find the intersection of two arrays.
• 407. Implement a function to check if a string can be segmented into a space-separated sequence of one or more dictionary words using hashing.
• 408. Write a program to find all duplicates in an array using a hash map.
• 409. Create a hash map that returns the indices of the two numbers that add up to a specific target in an array.
• 410. Implement a function to find the longest palindromic substring using hashing.
• 411. Write a program to find all pairs in an array that sum to a specific value using a hash table.
• 412. Create a hash table to store pairs of words that are anagrams of each other from a given list.
• 413. Implement a function to find the minimum window substring that contains all characters of another string using hashing.
• 414. Write a program to check if a sequence of parentheses is valid using a hash table.
• 415. Create a hash map to count the frequency of characters in a string and return the top K frequent characters.
• 416. Implement a function to find the length of the longest consecutive sequence of numbers in an unsorted array using a hash set.
• 417. Write a program to find all unique quadruplets in an array that sum to a target value using hashing.
• 418. Create a hash table to find the longest substring with at most two distinct characters using hashing.
• 419. Implement a function to find the first repeating element in an array using a hash map.
• 420. Write a program to check if a string contains all unique characters using a hash set.
• 421. Create a hash map to store the count of distinct elements in each sliding window of size K in an array.
• 422. Implement a function to find all substrings of a string that are palindromes using a hash map.
• 423. Write a program to check if two strings are rotations of each other using hashing.
• 424. Create a hash table to store the frequency of elements in a matrix and find the most frequent element.
• 425. Implement a function to find the length of the longest substring with at most K distinct characters using hashing.
• 426. Write a program to find the longest subarray with equal number of 0s and 1s using hashing.
• 427. Create a hash map to find the longest consecutive sequence of characters in a string.
• 428. Implement a function to find all elements in an array that appear more than once and their counts using hashing.
• 429. Write a program to determine if a string can be formed by rearranging another string using a hash table.
• 430. Create a hash table to store pairs of indices of two strings that are anagrams of each other.

• More Levels

• Beginner
• Intermediate