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 Dynamic Programming Tabulation

Proficient

Implement the `longestPalindromicSubsequenceLength` method that returns the length of the longest palindromic subsequence.

String Dynamic Programming Tabulation

Guru

Implement the `editDistanceSimple` method that returns the minimum edit operations needed to convert one string into another.

String Dynamic Programming Tabulation

Proficient

Implement the `longestCommonSubsequenceLength` method that returns the length of the longest common subsequence of two strings.

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.

String Manipulation String Counting Character

Intermediate

Implement the `firstNonRepeatingCharacter` method that returns the first character in the text that appears only once.

String Dynamic Programming Pattern Matching

Guru

Implement the method `isWildcardMatch` that checks whether a string matches a wildcard pattern.

String Hash Map Sliding Window

Guru

Implement the method `minimumWindowLength` that returns the length of the smallest substring containing all required characters.

String Dynamic Programming Recursion

Guru

Implement the method `editDistance` that returns the minimum number of edits needed to convert one string into another.

String Dynamic Programming

Proficient

Implement the method `countPalindromicSubstrings` that counts all palindromic substrings.

String Hash Map Sliding Window

Proficient

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

String Counting

Intermediate

Implement the method `compressRuns` that compresses consecutive repeated characters.

String Manipulation String

Intermediate

Implement the method `reverseWords` that reverses the order of words in a string.