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HomeLeetCode ProblemsStack

Stack Problems

140 Stack LeetCode problems · Solve with AI-powered hints & step-by-step explanations.

20Valid ParenthesesEasy32Longest Valid ParenthesesHard42Trapping Rain WaterHard71Simplify PathMedium84Largest Rectangle in HistogramHard85Maximal RectangleHard94Binary Tree Inorder TraversalEasy114Flatten Binary Tree to Linked ListMedium143Reorder ListMedium144Binary Tree Preorder TraversalEasy145Binary Tree Postorder TraversalEasy150Evaluate Reverse Polish NotationMedium155Min StackMedium173Binary Search Tree IteratorMedium224Basic CalculatorHard225Implement Stack using QueuesEasy227Basic Calculator IIMedium232Implement Queue using StacksEasy234Palindrome Linked ListEasy316Remove Duplicate LettersMedium321Create Maximum NumberHard331Verify Preorder Serialization of a Binary TreeMedium341Flatten Nested List IteratorMedium385Mini ParserMedium388Longest Absolute File PathMedium394Decode StringMedium402Remove K DigitsMedium445Add Two Numbers IIMedium456132 PatternMedium488Zuma GameHard496Next Greater Element IEasy503Next Greater Element IIMedium581Shortest Unsorted Continuous SubarrayMedium589N-ary Tree Preorder TraversalEasy590N-ary Tree Postorder TraversalEasy591Tag ValidatorHard636Exclusive Time of FunctionsMedium654Maximum Binary TreeMedium678Valid Parenthesis StringMedium682Baseball GameEasy726Number of AtomsHard735Asteroid CollisionMedium736Parse Lisp ExpressionHard739Daily TemperaturesMedium768Max Chunks To Make Sorted IIHard769Max Chunks To Make SortedMedium770Basic Calculator IVHard844Backspace String CompareEasy853Car FleetMedium856Score of ParenthesesMedium880Decoded String at IndexMedium895Maximum Frequency StackHard897Increasing Order Search TreeEasy901Online Stock SpanMedium907Sum of Subarray MinimumsMedium921Minimum Add to Make Parentheses ValidMedium936Stamping The SequenceHard946Validate Stack SequencesMedium962Maximum Width RampMedium975Odd Even JumpHard1003Check If Word Is Valid After SubstitutionsMedium1006Clumsy FactorialMedium1008Construct Binary Search Tree from Preorder TraversalMedium1019Next Greater Node In Linked ListMedium1021Remove Outermost ParenthesesEasy1047Remove All Adjacent Duplicates In StringEasy1081Smallest Subsequence of Distinct CharactersMedium1096Brace Expansion IIHard1106Parsing A Boolean ExpressionHard1111Maximum Nesting Depth of Two Valid Parentheses StringsMedium1124Longest Well-Performing IntervalMedium1130Minimum Cost Tree From Leaf ValuesMedium1172Dinner Plate StacksHard1190Reverse Substrings Between Each Pair of ParenthesesMedium1209Remove All Adjacent Duplicates in String IIMedium1249Minimum Remove to Make Valid ParenthesesMedium1381Design a Stack With Increment OperationMedium1441Build an Array With Stack OperationsMedium1472Design Browser HistoryMedium1475Final Prices With a Special Discount in a ShopEasy1504Count Submatrices With All OnesMedium1526Minimum Number of Increments on Subarrays to Form a Target ArrayHard1541Minimum Insertions to Balance a Parentheses StringMedium1544Make The String GreatEasy1574Shortest Subarray to be Removed to Make Array SortedMedium1598Crawler Log FolderEasy1614Maximum Nesting Depth of the ParenthesesEasy1653Minimum Deletions to Make String BalancedMedium1673Find the Most Competitive SubsequenceMedium1700Number of Students Unable to Eat LunchEasy1717Maximum Score From Removing SubstringsMedium1776Car Fleet IIHard1793Maximum Score of a Good SubarrayHard1856Maximum Subarray Min-ProductMedium1896Minimum Cost to Change the Final Value of ExpressionHard1910Remove All Occurrences of a SubstringMedium1944Number of Visible People in a QueueHard1963Minimum Number of Swaps to Make the String BalancedMedium1996The Number of Weak Characters in the GameMedium2000Reverse Prefix of WordEasy2019The Score of Students Solving Math ExpressionHard2030Smallest K-Length Subsequence With Occurrences of a LetterHard2104Sum of Subarray RangesMedium2116Check if a Parentheses String Can Be ValidMedium2130Maximum Twin Sum of a Linked ListMedium2197Replace Non-Coprime Numbers in ArrayHard2211Count Collisions on a RoadMedium2216Minimum Deletions to Make Array BeautifulMedium2281Sum of Total Strength of WizardsHard2289Steps to Make Array Non-decreasingMedium2296Design a Text EditorHard2334Subarray With Elements Greater Than Varying ThresholdHard2375Construct Smallest Number From DI StringMedium2390Removing Stars From a StringMedium2434Using a Robot to Print the Lexicographically Smallest StringMedium2454Next Greater Element IVHard2487Remove Nodes From Linked ListMedium2589Minimum Time to Complete All TasksHard2617Minimum Number of Visited Cells in a GridHard2645Minimum Additions to Make Valid StringMedium2696Minimum String Length After Removing SubstringsEasy2736Maximum Sum QueriesHard2751Robot CollisionsHard2813Maximum Elegance of a K-Length SubsequenceHard2816Double a Number Represented as a Linked ListMedium2818Apply Operations to Maximize ScoreHard2865Beautiful Towers IMedium2866Beautiful Towers IIMedium2940Find Building Where Alice and Bob Can MeetHard2945Find Maximum Non-decreasing Array LengthHard3113Find the Number of Subarrays Where Boundary Elements Are MaximumHard3170Lexicographically Minimum String After Removing StarsMedium3174Clear DigitsEasy3229Minimum Operations to Make Array Equal to TargetHard3412Find Mirror Score of a StringMedium3420Count Non-Decreasing Subarrays After K OperationsHard3430Maximum and Minimum Sums of at Most Size K SubarraysHard3523Make Array Non-decreasingMedium3542Minimum Operations to Convert All Elements to ZeroMedium3561Resulting String After Adjacent RemovalsMedium
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