Arrays problems

54 problems: 15 easy, 34 medium and 5 hard. Start at the top; each one assumes the ones above it.

Not startedEasyBest day to buy and sellDynamic programming, Arrays
Not startedEasyBuilding Pascal's triangle row by rowDynamic programming, Basics, Arrays
Not startedEasyContains duplicateArrays, Hash sets
Not startedEasyFind it by halvingArrays, Binary search
Not startedEasyMove the zeroes to the endArrays, Two pointers
Not startedEasyRunning sumArrays, Prefix sums
Not startedEasySearch insert positionArrays, Binary search
Not startedEasySqueeze out the duplicatesArrays, Two pointers
Not startedEasyThe best k days in a rowArrays, Sliding window
Not startedEasyThe next bigger number to the rightArrays, Stacks and queues
Not startedEasyThe number more than halfArrays, Hash maps
Not startedEasyThe number that appears onceBit manipulation, Arrays, Hash maps
Not startedEasyTwo sumArrays, Hash maps
Not startedEasyTwo sum in a sorted listTwo pointers, Binary search, Arrays
Not startedEasyWhat two lists have in commonArrays, Hash sets
Not startedMediumBinary search on a sorted list someone rotatedArrays, Binary search
Not startedMediumBlank out every row and column holding a zeroMatrices, Arrays
Not startedMediumCan it be split into two equal halvesDynamic programming, Arrays
Not startedMediumCan you get to the endArrays, Greedy
Not startedMediumCombine the ranges that overlapSorting, Arrays, Greedy
Not startedMediumEvery subset, in orderArrays, Backtracking
Not startedMediumEvery way to make the targetArrays, Backtracking
Not startedMediumFitting the most value into the bagDynamic programming, Arrays
Not startedMediumHow long this price has been the bestArrays, Stacks and queues
Not startedMediumHow long until it gets warmerArrays, Stacks and queues
Not startedMediumHow many must you dropSorting, Arrays, Greedy
Not startedMediumHow many triples add to zeroSorting, Arrays, Two pointers
Not startedMediumHow many ways down through the gridDynamic programming, Matrices, Arrays
Not startedMediumLongest run of consecutive numbersArrays, Hash sets
Not startedMediumMaximum subarray sumDynamic programming, Arrays
Not startedMediumMost frequent numbersSorting, Arrays, Heaps, Hash maps
Not startedMediumProduct of everything elseArrays, Prefix sums
Not startedMediumRead the grid in a spiralMatrices, Arrays
Not startedMediumSharing the books so nobody reads too muchArrays, Binary search
Not startedMediumShortest stretch that reaches the targetArrays, Sliding window
Not startedMediumSorting 0s, 1s and 2s in one passSorting, Arrays, Two pointers
Not startedMediumThe best you can take without touching neighboursDynamic programming, Arrays
Not startedMediumThe cheapest way down through the gridDynamic programming, Matrices, Arrays
Not startedMediumThe first negative number in every windowArrays, Sliding window, Stacks and queues
Not startedMediumThe kth largest, without sorting everythingArrays, Heaps
Not startedMediumThe longest run of ones, with k flipsArrays, Sliding window
Not startedMediumThe one number that is not repeated three timesBit manipulation, Arrays
Not startedMediumThe slowest speed that still finishes in timeArrays, Binary search
Not startedMediumThe smallest ship that still finishes in timeArrays, Binary search
Not startedMediumThe smallest value after a rotationArrays, Binary search
Not startedMediumThe widest, deepest containerArrays, Two pointers, Greedy
Not startedMediumTurn the square a quarter turnMatrices, Arrays
Not startedMediumTwo baskets, one row of treesArrays, Sliding window, Hash maps
Not startedMediumWhere a repeated value starts and endsBinary search, Arrays
Not startedHardHow far the list is from sortedSorting, Arrays
Not startedHardMerging many sorted lists at onceSorting, Arrays, Heaps
Not startedHardThe biggest rectangle inside a histogramArrays, Stacks and queues
Not startedHardThe largest number in every windowArrays, Sliding window, Stacks and queues
Not startedHardWater held between the barsTwo pointers, Stacks and queues, Arrays