Practice · judged on hidden tests

Problems

100 problems, ordered so each topic builds on the last.

Not startedA cache that forgets what you have not usedDesign, Linked lists, Hash mapsMedium
Not startedAn order you can actually take the courses inGraphs, Topological sortMedium
Not startedAre these two trees identicalTreesEasy
Not startedArithmetic without bracketsStrings, Stacks and queuesMedium
Not startedBest day to buy and sellArrays, Dynamic programmingEasy
Not startedBest run after k changesSliding window, StringsMedium
Not startedBinary search on a sorted list someone rotatedArrays, Binary searchMedium
Not startedBlank out every row and column holding a zeroArrays, MatricesMedium
Not startedBreak the loop and leave the listTwo pointers, Linked listsMedium
Not startedBuilding Pascal's triangle row by rowArrays, Basics, Dynamic programmingEasy
Not startedCancel out neighbouring pairsStrings, Stacks and queuesEasy
Not startedCan it be split into two equal halvesArrays, Dynamic programmingMedium
Not startedCan you get to the endArrays, GreedyMedium
Not startedCombine the ranges that overlapSorting, Arrays, GreedyMedium
Not startedContains duplicateHash sets, ArraysEasy
Not startedCount the islandsGraphs, MatricesMedium
Not startedCourse scheduleGraphs, Topological sortMedium
Not startedDoes this list loop back on itselfTwo pointers, Linked listsEasy
Not startedDrop the nth node from the endTwo pointers, Linked listsMedium
Not startedEvery arrangement of the letters, each one onceStrings, BacktrackingMedium
Not startedEvery subset, in orderBacktracking, ArraysMedium
Not startedEvery way the brackets can balanceStrings, BacktrackingMedium
Not startedEvery way to make the targetBacktracking, ArraysMedium
Not startedFewest coins to make the amountGreedy, Dynamic programmingMedium
Not startedFind it by halvingArrays, Binary searchEasy