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

Array Hash Map Counting

Learner

Implement the `countDistinctValues` method that counts how many different values are present in the array.

Array Hash Map Two Pointers

Intermediate

Implement the `hasPairWithExactDifference` method that checks whether any two values in the array have the required absolute difference.

Array Math Number Theory

Learner

Implement the `findMissingNumberFromOneToN` method that finds the missing value from a sequence that should contain numbers from 1 to n.

Learner

Implement the `rightRotateArrayByOne` method that returns the array after rotating all elements one position to the right.

Learner

Implement the `leftRotateArrayByOne` method that returns the array after rotating all elements one position to the left.

Loop Array Decision Making

Intermediate

Implement the `findSecondLargestDistinct` method that returns the second largest distinct value from the array.

Loop Array Two Pointers

Learner

Implement the `moveZerosToEndCopy` method that returns a copy of the array with all zero values moved to the end.

Loop Array Decision Making

Learner

Implement the `isArrayStrictlyIncreasing` method that checks whether every array element is greater than the element before it.

Loop Array Two Pointers

Learner

Implement the `reverseArrayCopy` method that returns a new array with the input elements in reverse order.

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.

Array Two Pointers

Proficient

Implement the method `trappedRainWater` that calculates how much water can be trapped between bars.

Array Dynamic Programming

Proficient

Implement the method `longestIncreasingSubsequence` that returns the length of the longest strictly increasing subsequence.

Math Dynamic Programming

Proficient

Implement the method `coinChangeMinCoins` that returns the minimum number of coins needed for an amount.

Proficient

Implement the method `minJumpsToEnd` that returns the fewest jumps needed to reach the last index.

String Hash Map Sliding Window

Proficient

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

Array Prefix Sum Dynamic Programming

Intermediate

Implement the method `maxSubarraySum` that returns the largest sum of any contiguous subarray.