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 Greedy

Learner

Implement the `canReachLastIndex` method that checks whether the last index can be reached from the first index.

Array Dynamic Programming Tabulation

Proficient

Implement the `minimumJumpsToReachEnd` method that finds the minimum jumps required to reach the last index.

Array Dynamic Programming Tabulation

Proficient

Implement the `rodCuttingMaximumProfit` method that finds the maximum profit obtainable by cutting a rod into pieces.

Array Dynamic Programming Matrix Tabulation

Intermediate

Implement the `uniquePathsWithBlockedCells` method that counts grid paths while avoiding blocked cells.

Array Dynamic Programming Matrix Tabulation

Intermediate

Implement the `minimumPathSumGrid` method that finds the minimum path sum from the top-left to the bottom-right of a grid.

Array Dynamic Programming Matrix Tabulation

Intermediate

Implement the `maximumPathSumGrid` method that finds the maximum path sum from the top-left to the bottom-right of a grid.

Array Dynamic Programming Tabulation

Proficient

Implement the `countSubsetSumWays` method that counts how many subsets produce the target sum.

Array Dynamic Programming Tabulation

Intermediate

Implement the `subsetSumExists` method that checks whether any subset can produce the target sum.

Array Dynamic Programming Tabulation

Proficient

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

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.

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.