Monotonic Stack LeetCode Problems: All 58, With Python Solutions

Every problem in this library that LeetCode tags Monotonic Stack — 58 in total, 47 of them with a complete Python solution, a worked example and the time and space complexity of the approach.

  • 58 problems
  • 2 Easy
  • 35 Medium
  • 21 Hard

How Monotonic Stack problems are solved

A tag names the subject, not the method. These pattern hubs cover the techniques that actually solve Monotonic Stack problems — each one explains the approach, gives a Python template and states its complexity.

  • Monotonic Stack — Answer "what is the next greater element" for every position in one pass.

Monotonic Stack problems by difficulty

Problems with a complete Python solution are listed first, then by ascending problem number.

Easy (2)

#ProblemDifficultyTopics
496Next Greater Element IEasyStack, Array, Hash Table +1
1475Final Prices With a Special Discount in a ShopEasyStack, Array, Monotonic Stack

Medium (35)

#ProblemDifficultyTopics
316Remove Duplicate LettersMediumStack, Greedy, String +1
402Remove K DigitsMediumStack, Greedy, String +1
456132 PatternMediumStack, Array, Binary Search +2
503Next Greater Element IIMediumStack, Array, Monotonic Stack
581Shortest Unsorted Continuous SubarrayMediumStack, Greedy, Array +3
654Maximum Binary TreeMediumStack, Tree, Array +3
739Daily TemperaturesMediumStack, Array, Monotonic Stack
769Max Chunks To Make SortedMediumStack, Greedy, Array +2
853Car FleetMediumStack, Array, Sorting +1
901Online Stock SpanMediumStack, Design, Data Stream +1
907Sum of Subarray MinimumsMediumStack, Array, Dynamic Programming +1
962Maximum Width RampMediumStack, Array, Two Pointers +1
1008Construct Binary Search Tree from Preorder TraversalMediumStack, Tree, Binary Search Tree +3
1019Next Greater Node In Linked ListMediumStack, Array, Linked List +1
1081Smallest Subsequence of Distinct CharactersMediumStack, Greedy, String +1
1124Longest Well-Performing IntervalMediumStack, Array, Hash Table +2
1130Minimum Cost Tree From Leaf ValuesMediumStack, Greedy, Array +2
1504Count Submatrices With All OnesMediumStack, Array, Dynamic Programming +2
1574Shortest Subarray to be Removed to Make Array SortedMediumStack, Array, Two Pointers +2
1673Find the Most Competitive SubsequenceMediumStack, Greedy, Array +1
1856Maximum Subarray Min-ProductMediumStack, Array, Prefix Sum +1
1996The Number of Weak Characters in the GameMediumStack, Greedy, Array +2
2104Sum of Subarray RangesMediumStack, Array, Monotonic Stack
2289Steps to Make Array Non-decreasingMediumStack, Array, Linked List +1
2487Remove Nodes From Linked ListMediumStack, Recursion, Linked List +1
2865Beautiful Towers IMediumStack, Array, Monotonic Stack
2866Beautiful Towers IIMediumStack, Array, Monotonic Stack
255Verify Preorder Sequence in Binary Search TreePremiumMediumStack, Tree, Binary Search Tree +4
1762Buildings With an Ocean ViewPremiumMediumStack, Array, Monotonic Stack
1950Maximum of Minimum Values in All SubarraysPremiumMediumStack, Array, Monotonic Stack
2282Number of People That Can Be Seen in a GridPremiumMediumStack, Array, Matrix +1
2297Jump Game VIIIPremiumMediumStack, Graph, Array +3
2345Finding the Number of Visible MountainsPremiumMediumStack, Array, Sorting +1
2832Maximal Range That Each Element Is Maximum in ItPremiumMediumStack, Array, Monotonic Stack
2863Maximum Length of Semi-Decreasing SubarraysPremiumMediumStack, Array, Sorting +1

Hard (21)

#ProblemDifficultyTopics
42Trapping Rain WaterHardStack, Array, Two Pointers +2
84Largest Rectangle in HistogramHardStack, Array, Monotonic Stack
85Maximal RectangleHardStack, Array, Dynamic Programming +2
321Create Maximum NumberHardStack, Greedy, Array +2
768Max Chunks To Make Sorted IIHardStack, Greedy, Array +2
975Odd Even JumpHardStack, Array, Dynamic Programming +3
1526Minimum Number of Increments on Subarrays to Form a Target ArrayHardStack, Greedy, Array +2
1776Car Fleet IIHardStack, Array, Math +2
1793Maximum Score of a Good SubarrayHardStack, Array, Two Pointers +2
1944Number of Visible People in a QueueHardStack, Array, Monotonic Stack
2281Sum of Total Strength of WizardsHardStack, Array, Prefix Sum +1
2334Subarray With Elements Greater Than Varying ThresholdHardStack, Union Find, Array +1
2454Next Greater Element IVHardStack, Array, Binary Search +3
2617Minimum Number of Visited Cells in a GridHardStack, Breadth-First Search, Union Find +5
2736Maximum Sum QueriesHardStack, Binary Indexed Tree, Segment Tree +4
2818Apply Operations to Maximize ScoreHardStack, Greedy, Array +4
2940Find Building Where Alice and Bob Can MeetHardStack, Binary Indexed Tree, Segment Tree +4
2945Find Maximum Non-decreasing Array LengthHardStack, Queue, Array +4
1063Number of Valid SubarraysPremiumHardStack, Array, Monotonic Stack
2030Smallest K-Length Subsequence With Occurrences of a LetterHardStack, Greedy, String +1
2355Maximum Number of Books You Can TakePremiumHardStack, Array, Dynamic Programming +1

Keep exploring

All LeetCode topicsEvery tag with a page of its own, with the number of problems behind each.LeetCode patternsThe techniques themselves, with a Python template and complexity for each.Curated study listsBlind 75, NeetCode 150 and three more, grouped by pattern.Easy problemsStart here when the data structure is new rather than the problem.
Other topics

When the Monotonic Stack problem arrives live

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