Stack coding problems

Stack problems cover balanced brackets, expression evaluation and the monotonic stack trick behind next greater element and largest rectangle questions.

29 problems: 13 easy, 13 medium, 3 hard. Free to read; a free account solves them and earns XP and Aura.

1. Find Previous Smaller ElementPractice · +10 XP · stack, monotonic stackeasy
2. Last Element in RangePractice · +10 XP · stack, arrayseasy
3. Max Element in PrefixPractice · +10 XP · stack, prefix sums, arrayseasy
4. Print Elements Larger Than PreviousPractice · +10 XP · stack, basic programming, iterationeasy
5. Print Previous Smaller ElementPractice · +10 XP · stackeasy
6. Print Stack SizePractice · +10 XP · stackeasy
7. Queue ReverserPractice · +10 XP · queue, stack, simulationeasy
8. Reverse a StringPractice · +10 XP · stack, stringeasy
9. Reverse First K ElementsPractice · +10 XP · queue, stack, simulationeasy
10. Simple Bracket CheckerPractice · +10 XP · stack, bracket matching, beginnereasy
11. Stack of IntegersPractice · +10 XP · stackeasy
12. Stack Push CounterPractice · +10 XP · stack, simulation, arrayseasy
13. Valid BracketsPractice · +10 XP · stack, stringseasy
14. Balanced Parentheses SubsequencePractice · +20 XP · queue, stack, simulationmedium
15. Distinct Elements in Sliding WindowPractice · +20 XP · stack, hash map, sliding windowmedium
16. Find Closest Smaller ElementPractice · +20 XP · stack, monotonic stack, arraymedium
17. Indices of Next Smaller ElementPractice · +20 XP · stack, monotonic stack, arraymedium
18. Largest Rectangle Under HistogramPractice · +20 XP · stack, monotonic stack, area calculationmedium
19. Longest Prefix with Equal CountsPractice · +20 XP · stack, hash map, prefix summedium
20. Maximum Sum of Non-Overlapping Positive SubarraysPractice · +20 XP · stack, dynamic programming, greedymedium
21. Next Greater Element in a Cyclic ArrayPractice · +20 XP · queue, stack, monotonic stackmedium
22. Next Greater Element on RightPractice · +20 XP · stack, monotonic stack, arraysmedium
23. Stack Maximum DifferencePractice · +20 XP · stack, monotonic stack, arraymedium
24. Subarray Sum RangePractice · +20 XP · stack, monotonic stack, prefix summedium
25. Sum of Minimums of All SubarraysPractice · +20 XP · stack, monotonic stack, prefix summedium
26. Sum of Next Greater Element PairsPractice · +20 XP · stack, array, monotonic stackmedium
27. Largest Rectangle in a HistogramPractice · +30 XP · monotonic stack, arrayshard
28. Longest Increasing Subsequence with Stack ConstraintPractice · +30 XP · stack, dynamic programming, greedyhard
29. Subarray Minimums with SumPractice · +30 XP · arrays, monotonic stack, prefix sumshard