Python
All Practice by Track
A broad catch-all sheet if you want to browse every current problem grouped by course track.
Python
62 problems#0001
Remove Duplicates Without Losing Orderlistssetsorderhashing
Easy10 XP#0002Group Records By Keydictlistsrecords
Easy10 XP#0003Count Word Frequencydictstringscounting
Easy10 XP#0004Flatten One Level of Nested Listslistsnested-dataloops
Easy10 XP#0005Sort Records By Scoresortingdictrecords
Easy10 XP#0006Parse Key-Value Linesstringsparsingdict
Medium15 XP#0007Safely Read a Nested Dictionary Valuedictnested-dataerrors
Medium15 XP#0051Slugify a Titlestringsparsingcleaning
Easy10 XP#0052Merge Default and User Configdictdefaultsconfiguration
Easy10 XP#0053Compute Sliding Window Averageslistssliding-windowprefix-sums
Medium15 XP#0068Parse Simple CSV Linesfilescsvstrings
Easy15 XP#0069Safe Divide With Exceptionsexceptionserror-handling
Easy10 XP#0070Count Calls With a Decoratordecoratorsfunctions
Medium20 XP#0071Yield Fixed-Size Batchesgeneratorsiteration
Medium15 XP#0072Bank Account Classoopclasses
Easy15 XP#0073Days Between Datesdatetimedates
Easy10 XP#0074Total Values From JSON Recordsjsondictparsing
Medium15 XP#0092Rotate a List Rightlistsslicing
Easy10 XP#0093Invert Dictionary to List Valuesdictgrouping
Medium20 XP#0094Basic Email Validatorstringsvalidation
Easy10 XP#0110Run-Length Encode Valueslistscompressioniteration
Medium20 XP#0111Nested Get With Dict Keys and List Indexesdictlistsnested-data
Medium20 XP#0112Top N Records by Keysortingrecords
Easy10 XP#0128Chunk a List Into Fixed Sizeslistsslicing
Easy10 XP#0129Flatten a Dictionary One Leveldictnested-data
Medium20 XP#0130Count Records by Two Fieldsdicttuplesgrouping
Medium20 XP#0146Parse Valid JSONL Recordsjsonexceptionsfiles
Medium20 XP#0147Days Between Datesdatetimestrings
Easy10 XP#0148Take First N Items From an Iterablegeneratorsiteration
Medium20 XP#0164CSV Totals by Categorycsvdictionariesfiles
Medium20 XP#0165Normalize Phone Digitsstringscleaning
Easy10 XP#0166Simple Bank Account Classoopclasses
Medium20 XP#0179Password Rule Checkerstringsvalidation
Easy10 XP#0180Running Average Streamiterationmath
Medium20 XP#0195Parse a Query Stringstringsdictionariesparsing
Medium20 XP#0196Merge Default Settingsdictionariesconfiguration
Easy10 XP#0211Generate Pascal Trianglepatternslistsdynamic programming
Medium20 XP#0212Right Triangle Star Patternpatternsstringsloops
Easy10 XP#0213Centered Star Pyramidpatternsstringsloops
Medium20 XP#0214Hollow Square Patternpatternsconditionalsstrings
Medium20 XP#0215Increasing Number Trianglepatternsnumbersstrings
Easy10 XP#0216Floyd's Trianglepatternsnumbersloops
Medium20 XP#0217Diagonal Matrix Patternpatternsmatrixloops
Medium20 XP#0218Spiral Number Matrixmatrixsimulationpatterns
Hard25 XP#0219Diamond Star Patternpatternsstringsloops
Medium20 XP#0220Zigzag String Rowsstringssimulation
Medium20 XP#0221Check Normalized Anagramsstringshash mapscounting
Easy10 XP#0222Balanced Bracketsstringsstack
Medium20 XP#0223Roman Numeral to Integerstringsparsing
Medium20 XP#0224Merge Overlapping Intervalslistssortingintervals
Medium20 XP#0225Wrap Text Into Linesstringsgreedy
Medium20 XP#0226Parse Error Log Countsstringsdictionarieslogs
Easy10 XP#0227Memoized Fibonaccirecursionmemoizationdynamic programming
Medium20 XP#0228Inventory Deltadictionariesdata transformation
Medium20 XP#0229Compare Semantic Versionsstringsparsingcomparison
Medium20 XP#0230Normalize URL Pathstringsstackpaths
Medium20 XP#0305Sudoku Solverbacktrackingmatrixrecursionsudoku
Hard25 XP#0306Factorial of a Numbermathloopsrecursion
Easy10 XP#0307Check If a Number Is Primemathloopsconditionals
Easy10 XP#0308Find the First Duplicate Elementlistssetsduplicates
Easy10 XP#0309Check a Normalized Palindromestringstwo pointerspalindrome
Easy10 XP#0310Group Anagramsstringshash mapanagrams
Medium20 XPDSA
108 problems#0031
Valid Parenthesesstackstringsleetcode-classic
Easy10 XP#0032Two Sum Indiceshash-maparraysleetcode-classic
Easy10 XP#0033Binary Searchbinary-searcharrayssorted-data
Easy10 XP#0034Merge Overlapping Intervalsintervalssortingarrays
Medium15 XP#0035Top K Frequent Valueshash-mapheapfrequency
Medium15 XP#0054Longest Substring Without Repeating Charactersstringssliding-windowhash-map
Medium20 XP#0055Maximum Subarray Sumarraysdynamic-programmingkadane
Medium20 XP#0056Flood Fill a Gridgriddfsbfs
Medium20 XP#0057Binary Tree Level Order Traversaltreesqueuebfs
Medium20 XP#0062Reverse a Linked Listlinked-listpointersiteration
Medium20 XP#0063Generate Permutationsbacktrackingrecursion
Medium20 XP#0064K Closest Points to Originheappriority-queue
Medium20 XP#0065Network Delay Timegraphsdijkstrashortest-path
Hard25 XP#0066Coin Change Minimum Coinsdp1d-dp
Medium20 XP#0067Unique Paths in a Griddp2d-dp
Medium20 XP#0095Remove Nth Node From Endlinked-listtwo-pointers
Medium20 XP#0096Daily Temperaturesstackmonotonic-stack
Medium20 XP#0097House Robberdp1d-dp
Medium20 XP#0113Search in Rotated Sorted Arraybinary-searcharrays
Medium20 XP#0114Generate All Subsetsbacktrackingrecursion
Medium20 XP#0115Number of Islandsgraphsgriddfs
Medium20 XP#0131Next Greater Elementstackmonotonic-stack
Medium20 XP#0132Product Except Selfarraysprefix-suffix
Medium20 XP#0133Minimum Path Sumdp2d-dp
Medium20 XP#0149Kth Largest With a Min Heapheaptop-k
Medium20 XP#0150Generate All Subsetsbacktrackingrecursion
Medium20 XP#0151Count Islands in a Gridgraphsdfsgrid
Medium20 XP#0167Shortest Path in an Unweighted Graphgraphsbfs
Medium20 XP#0168Coin Change Minimum Coinsdynamic programming1d dp
Medium20 XP#0169Reverse a Linked List Represented as Pairslinked listpointers
Medium20 XP#0181Course Schedule: Can Finishgraphstopological sort
Medium20 XP#0182Longest Palindromic Substringstringstwo pointers
Medium20 XP#0197Count Islands in a Gridgraphsdfsgrid
Medium20 XP#0198Maximum Product Subarrayarraysdynamic programming
Medium20 XP#0231Two Sum Indexesarrayshash maplookup
Easy10 XP#0232Three Sum Tripletsarrayssortingtwo pointers
Medium20 XP#0233Container With Most Waterarraystwo pointersgreedy
Medium20 XP#0234Longest Substring Without Repeating Charactersstringssliding windowhash map
Medium20 XP#0235Minimum Window Substringstringssliding windowfrequency map
Hard25 XP#0236Kth Largest Elementheappriority queuetop k
Medium20 XP#0237Binary Tree Inorder Traversaltreesdfsrecursion
Easy10 XP#0238Binary Tree Level Order Traversaltreesbfsqueue
Medium20 XP#0239Validate Binary Search Treetreesbstrecursion
Medium20 XP#0240Lowest Common Ancestor in a BSTtreesbstsearch
Medium20 XP#0241Trie Word Search and Prefixtriesstringsprefix tree
Medium20 XP#0242Count Connected Components with Union-Findgraphsunion finddisjoint set
Medium20 XP#0243Word Ladder Lengthgraphsbfsshortest path
Hard25 XP#0244Longest Common Subsequencedynamic programming2d dpstrings
Medium20 XP#0245Edit Distancedynamic programming2d dpstrings
Hard25 XP#0246Subsets With Duplicatesbacktrackingsubsetsduplicates
Medium20 XP#0247Counting Bitsbit manipulationdynamic programming
Easy10 XP#0248Single Number with XORbit manipulationxorarrays
Easy10 XP#0249Can Attend All Meetingsintervalssorting
Easy10 XP#0250Rotate Image Matrixmatrixarraysin-place
Medium20 XP#0251Search a 2D Matrixmatrixbinary search
Medium20 XP#0252Daily Temperaturesstackmonotonic stackarrays
Medium20 XP#0253Course Schedulegraphstopological sortcycle detection
Medium20 XP#0254Network Delay Timegraphsdijkstrashortest pathheap
Medium20 XP#0255Merge Overlapping Intervalsintervalssorting
Medium20 XP#0256Insert Intervalintervalsgreedy
Medium20 XP#0257Minimum Meeting Roomsintervalsheapscheduling
Medium20 XP#0258Product of Array Except Selfarraysprefixsuffix
Medium20 XP#0259Search in Rotated Sorted Arraybinary searcharrays
Medium20 XP#0260Find First and Last Positionbinary searchboundaries
Medium20 XP#0261Koko Eating Bananasbinary search on answergreedy
Medium20 XP#0262Largest Rectangle in Histogramstackmonotonic stack
Hard25 XP#0263Evaluate Reverse Polish Notationstackexpression evaluation
Medium20 XP#0264Decode Stringstackstringsparsing
Medium20 XP#0265Combination Sumbacktrackingcombinations
Medium20 XP#0266Palindrome Partitioningbacktrackingstringspalindrome
Medium20 XP#0267Number of Islandsgraphsgriddfs
Medium20 XP#0268Rotting Orangesgraphsgridbfs
Medium20 XP#0269Word Breakdynamic programmingstrings
Medium20 XP#0270House Robber IIdynamic programmingcircular array
Medium20 XP#0271Coin Change IIdynamic programmingcombinations
Medium20 XP#0272Cheapest Flights Within K Stopsgraphsshortest pathdynamic programming
Medium20 XP#0273Merge Two Sorted Linked Listslinked listtwo pointersmerge
Easy10 XP#0274Linked List Cycle Detectionlinked listfast slow pointerscycle detection
Easy10 XP#0275Maximum Depth of Binary Treetreesdfsrecursion
Easy10 XP#0276Path Sumtreesdfsrecursion
Easy10 XP#0277Diameter of Binary Treetreesdfsrecursion
Medium20 XP#0278Longest Increasing Subsequencedynamic programmingbinary search
Medium20 XP#0279Partition Equal Subset Sumdynamic programmingsubset sum
Medium20 XP#0280Decode Waysdynamic programmingstrings
Medium20 XP#0281Maximal Squaredynamic programmingmatrix
Medium20 XP#0282Jump Gamegreedyarrays
Medium20 XP#0283Gas Stationgreedyarrays
Medium20 XP#0284Running Median Streamheapmedianstream
Hard25 XP#0285Permutations of Distinct Numbersbacktrackingpermutations
Medium20 XP#0286Word Searchbacktrackinggriddfs
Medium20 XP#0287Minimum Spanning Tree Costgraphsunion findmstgreedy
Hard25 XP#0288Pacific Atlantic Water Flowgraphsgriddfs
Medium20 XP#0289Longest Consecutive Sequencehash setarrayssequence
Medium20 XP#0290Subarray Sum Equals Kprefix sumhash maparrays
Medium20 XP#0291Trapping Rain Watertwo pointersarraysprefix suffix
Hard25 XP#0292Spiral Matrix Ordermatrixsimulation
Medium20 XP#0293Set Matrix Zeroesmatrixmarkers
Medium20 XP#0294Valid Sudoku Boardhash setmatrixvalidation
Medium20 XP#0295Alien Dictionary Ordergraphstopological sortstrings
Hard25 XP#0296Redundant Connectiongraphsunion findcycle detection
Medium20 XP#0297Accounts Mergeunion findgraphshash map
Medium20 XP#0298Surrounded Regionsgraphsgriddfs
Medium20 XP#0299Word Search IItriebacktrackinggrid
Hard25 XP#0300N-Queens Countbacktrackingsets
Hard25 XP#0301Candygreedytwo passes
Hard25 XP#0302Partition Labelsgreedystrings
Medium20 XP#0303Interleaving Stringdynamic programmingstrings
Hard25 XP#0304Distinct Subsequencesdynamic programmingstrings
Hard25 XPNumPy
20 problems#0008
Standardize a Numeric Columnnumpypreprocessingmeanstandard-deviation
Easy10 XP#0036Select Positive Valuesnumpyboolean-indexingarrays
Easy10 XP#0037Normalize Each Rownumpybroadcastingmatrix
Medium15 XP#0038Pairwise Distances To a Query Pointnumpybroadcastingknndistance
Medium15 XP#0058Min-Max Scale an Arraynumpyscalingpreprocessing
Easy15 XP#0075Add Column Offsets With Broadcastingnumpybroadcasting
Easy15 XP#0076Mask Values Above a Thresholdnumpymaskingfiltering
Easy10 XP#0098Column Means Ignoring NaNnumpynanaggregation
Easy10 XP#0099Scale Rows With Multipliersnumpybroadcasting
Medium20 XP#0116Take Selected Columnsnumpyindexing
Easy10 XP#0117Binary Confusion Matrix With NumPynumpymetricsboolean-masks
Medium20 XP#0134Replace NaN With Column Meannumpynanimputation
Medium20 XP#0135Argmax Per Rownumpyaxisargmax
Easy10 XP#0152Clamp Values to a Rangenumpyvectorizationmasking
Easy10 XP#0153Batch Dot Productsnumpylinear algebra
Medium20 XP#0170Filter Rows With a Boolean Masknumpymasking
Easy10 XP#0183One-Hot Encode Integer Labelsnumpyencoding
Medium20 XP#0184Cosine Similarity Between Vectorsnumpyvectorssimilarity
Medium20 XP#0199Standardize Columnsnumpyfeature scaling
Medium20 XP#0200Pairwise L1 Distancenumpybroadcastingdistance
Medium20 XPPandas
20 problems#0009
Find Revenue By Categorypandasgroupbyaggregation
Easy10 XP#0039Filter Active High-Value Userspandasfilteringboolean-mask
Easy10 XP#0040Fill Missing Values By Group Medianpandasmissing-valuesgroupbytransform
Medium15 XP#0041Left Join Orders With Customerspandasmergejoins
Easy10 XP#0060Keep Latest Event Per Userpandasdeduplicationsorting
Medium20 XP#0081Pivot Sales by Region and Productpandaspivotaggregation
Medium20 XP#0082Melt Wide Score Columnspandasmeltreshape
Medium20 XP#0100Revenue Share Within Grouppandasgroupbytransform
Medium20 XP#0101Inner Join Users and Eventspandasjoins
Easy10 XP#0118Rolling Average by Userpandasrollingtime-series
Medium20 XP#0119Flag Duplicate Rows by Keypandasduplicatesdata-quality
Easy10 XP#0136Top N Rows Per Grouppandasgroupbyranking
Medium20 XP#0137Wide Monthly Sales to Longpandasmeltreshape
Medium20 XP#0154Cumulative Sales by Customerpandasgroupbycumsum
Medium20 XP#0155Keep Latest Record per Entitypandasdeduplicationsorting
Medium20 XP#0171Percent of Group Totalpandasgroupbytransform
Medium20 XP#0185Left Anti Join in Pandaspandasjoins
Medium20 XP#0186Rolling Average Salespandastime seriesrolling
Medium20 XP#0201Top Product per Categorypandasgroupbyranking
Medium20 XP#0202Fill Missing Values by Group Medianpandasmissing valuestransform
Medium20 XPML
33 problems#0010
Build a Confusion Matrixclassificationmetricsevaluation
Easy10 XP#0011One Step of Gradient Descentoptimizationgradient-descentlinear-regression
Medium15 XP#0012Sigmoid Converts Scores To Probabilitieslogistic-regressionsigmoidprobability
Easy10 XP#0013Stable Softmaxsoftmaxclassificationnumerical-stability
Medium15 XP#0014Binary Cross Entropy Lossloss-functionsclassificationlog-loss
Medium15 XP#0015Precision, Recall, and F1classificationmetricsimbalanced-data
Medium15 XP#0016Assign Points To Nearest Centroidk-meansclusteringdistances
Medium15 XP#0017ReLU Forward Passdeep-learningactivation-functionsnumpy
Easy10 XP#0018Dense Layer Forward Passdeep-learningmatrix-multiplicationnumpy
Medium15 XP#0019Convolution Output Sizedeep-learningcnnconvolution
Medium15 XP#0020Binary Cross Entropy From Probabilitiesdeep-learningloss-functionsclassification
Medium15 XP#0021Convert RGB Image To Grayscalecomputer-visionimage-processingnumpy
Easy10 XP#0022Resize Image With Nearest Neighborcomputer-visionresizingnumpy
Medium15 XP#0023Bounding Box IoUcomputer-visionobject-detectioniou
Medium15 XP#0024CNN Output Volume Shapecomputer-visioncnnshape-reasoning
Medium15 XP#0059Deterministic Train-Test Split Indicessplittingevaluationrandomness
Medium20 XP#0077One-Hot Encode a Categorical Columnfeature-encodingcategorical-data
Medium20 XP#0078Detect Suspicious Leakage Columnsleakagevalidation
Easy15 XP#0079MAE and RMSEmetricsregression
Easy15 XP#0080L2 Regularized Lossregularizationloss
Medium20 XP#0104TPR and FPR From Countsmetricsclassification
Easy10 XP#0105Fit and Apply Standard Scalerpreprocessingscaling
Medium20 XP#0120Threshold Probabilitiesclassificationthresholds
Easy10 XP#0121Label Encode Train and Testencodingcategorical-data
Medium20 XP#0138Min-Max Scale Train and Testpreprocessingleakage
Medium20 XP#0139Majority Class Baseline Accuracybaselineclassification
Easy10 XP#0156Check Stratified Split Countsevaluationclassificationsplits
Medium20 XP#0157Compute Ridge Penalty Termregularizationlinear models
Easy10 XP#0172Label Encode Train and Test Safelyencodingpreprocessing
Medium20 XP#0187Mean Absolute Errormetricsregression
Easy10 XP#0188Remove Leakage Featuresleakagefeature engineering
Medium20 XP#0203Binary Confusion Matrixmetricsclassification
Medium20 XP#0204Train/Test Split by Timevalidationtime seriesleakage
Medium20 XPSQL
109 problems#0025
Customers With No Orderssqlleft-joinanti-join
Easy10 XP#0026Top Product Per Categorysqlwindow-functionsranking
Medium15 XP#0027Categories Over Revenue Thresholdsqlgroup-byhaving
Easy10 XP#0028Running Revenue By Daysqlwindow-functionsrunning-total
Medium15 XP#0029Find Duplicate Emailssqlduplicatesgroup-by
Easy10 XP#0030Day-One Retentionsqlretentionself-join
Medium15 XP#0061Second Highest Salarysqlrankingdistinct
Medium15 XP#0083Customers With Recent Orderssqljoinsdate-filtering
Medium15 XP#0084Monthly Revenue With CTEsqlcteaggregation
Medium15 XP#0085Rank Products by Revenuesqlwindow-functionsranking
Medium20 XP#0102Average Ignoring NULL Scoressqlnullsaggregation
Easy10 XP#0103Cohort Month Zerosqlcohortdates
Medium20 XP#0122Signup to Purchase Funnelsqlfunnelaggregation
Medium20 XP#0123Latest Row Per User With ROW_NUMBERsqlwindow-functionsdeduplication
Medium20 XP#0140Users With No Eventssqlleft-joinnulls
Easy10 XP#0141Seven Day Active Userssqldatesdistinct
Medium20 XP#0158Second Highest Salarysqlrankingwindow functions
Medium20 XP#0159Monthly Active Userssqldatesaggregation
Medium20 XP#0173Customers Above Average Spendsqlcteaggregation
Medium20 XP#0174Find Rows Without Matches Using NOT EXISTSsqlnullsanti join
Medium20 XP#0189First Purchase Date per Usersqlaggregation
Easy10 XP#0190Users With Repeat Purchasessqlhaving
Medium20 XP#0205Average Order Value by Usersqlgroup byaggregation
Easy10 XP#0206Second Purchase Datesqlwindow functionsranking
Medium20 XP#0311Filter Paid Orders Above a Minimumsqlwherefiltering
Easy10 XP#0312Sort Products by Price Then Namesqlorder-bysorting
Easy10 XP#0313Distinct Active Userssqldistinct
Easy10 XP#0314Count Orders Per Statussqlgroup-byaggregation
Easy10 XP#0315Total Revenue Per Customersqlgroup-bysum
Easy10 XP#0316Customers With More Than Two Orderssqlgroup-byhaving
Easy10 XP#0317Join Orders to Customer Namessqljoinsinner-join
Easy10 XP#0318Customer Order Counts Including Zerosqlleft-joinaggregation
Medium20 XP#0319Products Never Soldsqlleft-joinanti-join
Easy10 XP#0320Orders Without Refundssqlnot-existsanti-join
Medium20 XP#0321Employee Manager Namessqlself-join
Medium20 XP#0322Revenue After Optional Discountssqlnullscoalesce
Easy10 XP#0323Bucket Orders by Amountsqlcasecategorization
Easy10 XP#0324Conditional Counts by Statussqlcaseaggregation
Medium20 XP#0325Distinct Products Per Usersqlcount-distinctaggregation
Easy10 XP#0326Departments With High Average Salarysqlhavingavg
Easy10 XP#0327Latest Login Per Usersqlwindow-functionsrow-number
Medium20 XP#0328Dense Rank Scoressqlwindow-functionsranking
Medium20 XP#0329Rank With Gapssqlwindow-functionsrank
Medium20 XP#0330Previous Order Amountsqlwindow-functionslag
Medium20 XP#0331Next Login Datesqlwindow-functionslead
Medium20 XP#0332Running Event Countsqlwindow-functionsrunning-total
Medium20 XP#0333Percent of Total Revenuesqlwindow-functionspercentage
Medium20 XP#0334Assign Revenue Quartilessqlwindow-functionsntile
Medium20 XP#0335Category Winner With FIRST_VALUEsqlwindow-functionsfirst-value
Medium20 XP#0336Monthly Signupssqldatesaggregation
Easy10 XP#0337Days Between First and Last Eventsqldatesaggregation
Medium20 XP#0338Seven Day Retentionsqlretentiondatesjoins
Medium20 XP#0339Cohort Size by Signup Monthsqlcohortdates
Easy10 XP#0340Funnel Step Countssqlfunnelaggregation
Medium20 XP#0341Users Completing Full Funnelsqlfunnelhaving
Medium20 XP#0342Cart Abandonerssqlfunnelanti-join
Medium20 XP#0343Union Active Users From Two Sourcessqlunionset-operations
Easy10 XP#0344Union All Event Volumesqlunion-allset-operations
Easy10 XP#0345Users Active on Web and Appsqlintersectset-operations
Easy10 XP#0346Web Only Userssqlexceptset-operations
Easy10 XP#0347All Product Color Combinationssqlcross-join
Easy10 XP#0348Orders Above Average Amountsqlsubqueryaverage
Medium20 XP#0349Products Equal to Category Maxsqlcorrelated-subquery
Medium20 XP#0350CTE User Revenue Filtersqlcteaggregation
Medium20 XP#0351Recursive CTE Countdownsqlrecursive-cte
Hard25 XP#0352Pivot Status Counts With CASEsqlcasepivot
Medium20 XP#0353Unpivot Quarter Salessqlunion-allunpivot
Medium20 XP#0354Avoid NOT IN With NULL Trapsqlnullsnot-exists
Medium20 XP#0355WHERE Before GROUP BYsqlwheregroup-by
Easy10 XP#0356Prevent Join Duplicate Explosionsqljoinspre-aggregation
Medium20 XP#0357Deduplicate Events Keep Firstsqlwindow-functionsdeduplication
Medium20 XP#0358Simple Sessionization by Gapsqlwindow-functionssessions
Hard25 XP#0359Users With Consecutive Login Dayssqlself-joindates
Medium20 XP#0360Top Two Products Per Categorysqlwindow-functionstop-n
Medium20 XP#0361Lowest Revenue Product Per Categorysqlwindow-functionsranking
Medium20 XP#0362Users Above Global Average Orderssqlctesubquery
Medium20 XP#0363First Date Cumulative Revenue Crosses Thresholdsqlwindow-functionsrunning-total
Hard25 XP#0364Rolling Three Day Revenuesqlwindow-functionsrolling-window
Hard25 XP#0365Most Common Countrysqlgroup-byranking
Medium20 XP#0366Median Value for Odd Row Countsqlwindow-functionsmedian
Hard25 XP#0367Filter Key Value Settingssqlfilteringkey-value
Easy10 XP#0368Daily New Users by First Eventsqlctedatesaggregation
Medium20 XP#0369Reactivated Users After Long Gapsqlwindow-functionsdatesretention
Hard25 XP#0370Churned Users With No Recent Eventsqldatesaggregation
Medium20 XP#0371Users With Multiple Event Typessqlgroup-bycount-distinct
Easy10 XP#0372Same Day Repeat Purchaserssqlgroup-byhaving
Medium20 XP#0373Find Missing Dates From Calendarsqlleft-joindates
Medium20 XP#0374Retention Rate by Cohortsqlretentioncohortaggregation
Hard25 XP#0375Visit to Purchase Conversion Ratesqlfunnelconversion-rate
Hard25 XP#0376Product Share Within Categorysqlwindow-functionspercentage
Medium20 XP#0377Customers Bought A but Not Bsqlanti-joinexists
Medium20 XP#0378Users With All Required Eventssqlrelational-divisionhaving
Medium20 XP#0379Preview Price Increasesqlcalculationselect
Easy10 XP#0380Preview Orphan Orderssqldata-qualityleft-join
Medium20 XP#0381Difference From Category Averagesqlwindow-functionsavg
Medium20 XP#0382Latest Non-NULL Measurement Datesqlnullsaggregation
Medium20 XP#0383Customers With Exactly One Ordersqlgroup-byhaving
Easy10 XP#0384Users With No Purchases After Signupsqlleft-joindatesanti-join
Medium20 XP#0385Cancellation Rate by Categorysqlcaseaggregationrate
Medium20 XP#0386Revenue Per Active Usersqlaggregationdistinctmetric
Medium20 XP#0387Products With Price Increasesqlwindow-functionslag
Medium20 XP#0388First Order Amount Per Usersqlwindow-functionsfirst-event
Medium20 XP#0389Simple Customer Lifetime Valuesqlaggregationmetric
Easy10 XP#0390Refund Adjusted Revenuesqljoinsaggregationmetric
Medium20 XP#0391SLA Breached Ticketssqlcasefiltering
Easy10 XP#0392Retention Matrix Cellsqlcohortretentiondates
Hard25 XP#0393Pairs of Users in Same Countrysqlself-joinpairs
Medium20 XP#0394Cumulative Users by Signup Daysqlwindow-functionsrunning-total
Medium20 XP#0395Latest Status Per Ordersqlwindow-functionsdeduplication
Medium20 XPAptitude
22 problems#0042
Combined Work Ratetime-and-workrates
Easy10 XP#0043Use HCF and LCM Product Relationshiphcflcmnumbers
Easy10 XP#0044Train Crossing a Platformtrainsspeed-distance-time
Medium15 XP#0045Direction Sense Final Positiondirection-sensereasoning
Easy10 XP#0046Circular Seating Neighbor Ruleseating-arrangementlogic
Medium15 XP#0086Profit, Loss and Marked Priceprofit-losspercentages
Easy10 XP#0087Probability With Two Diceprobability
Easy10 XP#0088Ratio Based Partnership Shareratiopartnership
Easy10 XP#0106Successive Percentage Changepercentages
Easy10 XP#0107Linear Seating Orderarrangementsreasoning
Medium20 XP#0124Mixture Average Pricemixturesweighted-average
Medium20 XP#0125Arrange Letters With Repetitionpermutationscounting
Medium20 XP#0142Simple Interestinterestpercentages
Easy10 XP#0143Age Ratio After Yearsagesratio
Medium20 XP#0160Profit After Discountprofit losspercentages
Medium20 XP#0161Probability of Sum Greater Than 9probabilitycounting
Medium20 XP#0175Arrange Letters With Repetitionpermutationscounting
Medium20 XP#0176Boat Speed in Still Waterspeedboats and streams
Medium20 XP#0191Compound Interest for Two Yearscompound interestpercentages
Medium20 XP#0192Clock Angle at 3:20clockangles
Medium20 XP#0207Average Speed for a Round Tripspeed distance timeaverages
Medium20 XP#0208Direction Sense: Final Positiondirection sensedistance
Easy10 XPR
21 problems#0047
Mean With Missing Valuesrmissing-valuesmean
Easy10 XP#0048Filter Rows in a Data Framerdata-framefiltering
Easy10 XP#0049Grouped Summary by Categoryraggregationgroup-by
Medium15 XP#0050Left Join with mergerjoinsmerge
Medium15 XP#0089Standardize an R Vectorrvectorsscaling
Easy10 XP#0090Count Factor Levelsrfactorscounts
Easy10 XP#0091Clean Missing Values in Rrmissing-valuesdata-cleaning
Easy10 XP#0108Basic Scatter Plot in Rrplotting
Easy10 XP#0109Subset Data Frame With Conditionsrfilteringdata-frame
Easy10 XP#0126Create Summary Data Frame in Rrdata-framesummary
Easy10 XP#0127Order a Data Frame in Rrsorting
Easy10 XP#0144Add a Derived Column in Rrdata-framemutate
Easy10 XP#0145Remove Rows With Missing Valuesrmissing-valuescleaning
Easy10 XP#0162Count Factor Levels in Rrfactorstables
Easy10 XP#0163Create a Category With ifelse in Rrdata cleaningifelse
Easy10 XP#0177Mean by Group With aggregate in Rraggregation
Easy10 XP#0178Parse a Date Column in Rrdatescleaning
Easy10 XP#0193Recode Status Values in Rrdata cleaning
Easy10 XP#0194Remove Duplicate Rows in Rrdeduplication
Easy10 XP#0209Order Factor Levels in Rrfactorsordering
Easy10 XP#0210Left Join Customers and Orders in Rrjoinsdplyr
Medium20 XP