Code Challenges

Get better at coding with practice problems.

Coding Challenges

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

Array Dynamic Programming Tabulation

Proficient

Implement the `canPartitionEqualSum` method that checks whether the array can be split into two subsets with equal sum.

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.

Array Dynamic Programming Tabulation

Proficient

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

Array Math Dynamic Programming Tabulation

Proficient

Implement the `minimumCoinsToMakeAmount` method that finds the minimum number of coins required to make the target amount.

Array Math Dynamic Programming Tabulation

Proficient

Implement the `countWaysToMakeAmount` method that counts how many combinations can make the target amount using coins.

Array Dynamic Programming Tabulation

Intermediate

Implement the `maximumNonAdjacentSum` method that finds the maximum sum using values that are not adjacent.

Array Dynamic Programming Tabulation

Learner

Implement the `minimumCostToClimb` method that finds the minimum cost needed to reach the top of the stairs.

Math Dynamic Programming Memoization Tabulation

Learner

Implement the `fibonacciDP` method that returns the nth Fibonacci number using dynamic programming.

Dynamic Programming Recursion Memoization Tabulation

Learner

Implement the `climbStairsWays` method that returns the number of distinct ways to climb n stairs.

Array Counting Sorting Two Pointers

Intermediate

Implement the `sortColorsThreeValues` method that sorts an array containing only three possible values.

Array Sorting Two Pointers

Guru

Implement the `findMedianOfTwoSortedArraysSimple` method that returns the floor of the median after combining two sorted arrays.

Array Counting Binary Search

Intermediate

Implement the `searchRangeOfTarget` method that returns the first and last position of a target in a sorted array.

Array Sorting Merge Sort

Proficient

Implement the `countInversionsInArray` method that counts pairs that are out of sorted order in the array.

Array Hash Map Sorting

Intermediate

Implement the `minimumSwapsToSortSmallArray` method that returns the minimum number of swaps needed to sort the array.

Array Sorting Two Pointers

Learner

Implement the `mergeSortedWithoutDuplicates` method that merges two sorted arrays while removing duplicate values.

Array Sorting Two Pointers

Learner

Implement the `findPairWithSortedSum` method that checks whether a sorted array contains a pair with the required sum.

Intermediate

Implement the `kthSmallestValue` method that returns the kth smallest value from the array.

Array Hash Map Counting Sorting

Intermediate

Implement the `sortByFrequencyAscending` method that sorts values by increasing frequency while resolving ties consistently.