Code Challenges

Coding Challenges

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

Learner

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

Learner

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

Learner

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

Proficient

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

Intermediate

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

Learner

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

Intermediate

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

Intermediate

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

Learner

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

Intermediate

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

Learner

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

Intermediate

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

Intermediate

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

Intermediate

Code Challenges

Get better at coding with practice problems.

Coding Challenges

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

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

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

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

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

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

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

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

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

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

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

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

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

Implement the method `firstNonRepeatingChar` that returns the first non-repeating character in a string.

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Practice Tests

Development Tools

Code Challenges

Get better at coding with practice problems.

Coding Challenges

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

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

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

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

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

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

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

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

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

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

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

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

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

Implement the method firstNonRepeatingChar that returns the first non-repeating character in a string. Solved

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

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

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

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

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

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

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

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

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

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

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

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

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

Implement the method `firstNonRepeatingChar` that returns the first non-repeating character in a string.