Code Challenges

Get better at coding with practice problems.

Coding Challenges

Select a problem, write code, run test cases, and submit your solution.

Start with beginner challenges

String Manipulation String

Intermediate

Implement the `multiplyLargeNumbersString` method that multiplies two non-negative integers represented as strings.

String Manipulation String Hash Map Counting Character Pattern Matching

Learner

Implement the `romanNumeralToInteger` method that converts a Roman numeral string into an integer.

String Manipulation String Hash Map Counting Character Pattern Matching

Learner

Implement the `checkStringRotation` method that checks whether one string is a rotation of another string.

String Manipulation String Hash Map Counting Character Pattern Matching

Learner

Implement the `firstUniqueCharacterIndex` method that returns the index of the first character that appears only once.

String Manipulation String Hash Map Counting Character Pattern Matching

Proficient

Implement the `minimumWindowContainsPatternLength` method that returns the length of the smallest substring containing all pattern characters.

String Manipulation String Hash Map Counting Character Pattern Matching

Intermediate

Implement the `stringCompressionLength` method that returns the length after compressing consecutive repeated characters.

String Manipulation String Hash Map Counting Character Pattern Matching

Learner

Implement the `validPalindromeAlphanumeric` method that checks whether a text is a palindrome after ignoring non-alphanumeric characters.

String Manipulation String Hash Map Counting Character Pattern Matching

Intermediate

Implement the `longestPalindromicSubstringLength` method that returns the length of the longest palindromic substring.

String Manipulation String Hash Map Counting Character Pattern Matching

Intermediate

Implement the `groupAnagramCount` method that counts how many anagram groups are formed from the words.

String Manipulation String Hash Map Counting Character Pattern Matching

Learner

Implement the `validAnagramCheck` method that checks whether two strings are anagrams.

String Manipulation String Hash Map Counting Character Pattern Matching

Intermediate

Implement the `longestSubstringNoRepeat` method that returns the length of the longest substring without repeated characters.

String Manipulation Loop String Pattern Matching

Intermediate

Implement the `countPatternOccurrences` method that counts how many times a pattern appears inside the given text.

String Manipulation String Conversion Bit Manipulation

Learner

Implement the `binaryStringToDecimal` method that converts a binary string into its decimal integer value.

String Manipulation String Stack Simulation

Learner

Implement the `removeAdjacentDuplicates` method that removes adjacent duplicate characters using stack-style processing.

String Manipulation String Two Pointers

Learner

Implement the `isSubsequenceText` method that checks whether the smaller text appears as a subsequence inside the larger text.

String Manipulation String Counting Sliding Window

Intermediate

Implement the `longestSubstringWithoutRepeat` method that returns the length of the longest substring that has no repeated characters.

String Manipulation String Pattern Matching

Learner

Implement the `isRotationOfString` method that checks whether one string can be formed by rotating the other string.

String Manipulation String Counting Character

Learner

Implement the `removeDuplicateCharacters` method that returns the text after keeping only the first occurrence of each character.

String Manipulation String Counting Character

Intermediate

Implement the `areTextsAnagram` method that checks whether two texts contain the same characters with the same frequencies.