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 Sorting Binary Search Two Pointers

Proficient

Implement the `medianTwoSortedArraysFloor` method that returns the floor of the median of two sorted arrays.

Array Sorting Binary Search Two Pointers

Intermediate

Implement the `findMinimumRotatedSorted` method that returns the minimum value from a rotated sorted array.

Array Sorting Binary Search Two Pointers

Proficient

Implement the `mergeSortInversionCount` method that counts inversions using merge-sort style processing.

Array Sorting Binary Search Two Pointers

Intermediate

Implement the `kthLargestQuickSelect` method that returns the kth largest value using selection logic.

Array Sorting Binary Search Two Pointers

Intermediate

Implement the `firstAndLastPositionBinary` method that returns the first and last target positions using binary search.

Array Sorting Binary Search Two Pointers

Intermediate

Implement the `searchRotatedSortedArrayImportant` method that searches for a target in a rotated sorted array using binary search.

Loop Array Hash Map Counting Prefix Sum

Intermediate

Implement the `nextPermutationRankChange` method that returns the next lexicographical permutation of the array.

Loop Array Hash Map Counting Prefix Sum

Learner

Implement the `maximumConsecutiveOnes` method that returns the longest run of consecutive 1 values.

Loop Array Hash Map Counting Prefix Sum

Intermediate

Implement the `mergeOverlappingIntervalsCount` method that returns how many intervals remain after merging all overlaps.

Loop Array Hash Map Counting Prefix Sum

Learner

Implement the `missingNumberZeroToN` method that finds the missing number from the range 0 to n.

Loop Array Hash Map Counting Prefix Sum

Learner

Implement the `findDuplicateNumber` method that returns a duplicate value from the array.

Loop Array Hash Map Counting Prefix Sum

Intermediate

Implement the `rotateArrayRightK` method that returns the array after rotating it k positions to the right.

Loop Array Hash Map Counting Prefix Sum

Intermediate

Implement the `productArrayExceptSelf` method that returns an array where each value is the product of all other values.

Loop Array Hash Map Counting Prefix Sum

Learner

Implement the `majorityElementValue` method that returns the value that appears more than half of the time.

Loop Array Hash Map Counting Prefix Sum

Intermediate

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

Loop Array Hash Map Counting Prefix Sum

Learner

Implement the `findTwoSumIndices` method that returns indices of two numbers whose sum equals the target.

Array Dynamic Programming Greedy

Intermediate

Implement the `maximumProfitMultipleTransactions` method that returns the maximum stock profit using multiple valid transactions.

Array Dynamic Programming Greedy

Learner

Implement the `maximumProfitSingleTransaction` method that returns the best stock profit using at most one buy and one sell.

Array Dynamic Programming Matrix Tabulation

Proficient

Implement the `maximumSquareOfOnes` method that returns the area of the largest square containing only 1 values.