Stacks and Queues

Serial No.	Questions
1	Implement Stack from Scratch
2	Implement Queue from Scratch
3	Implement 2 stack in an array
4	find the middle element of a stack
5	Implement "N" stacks in an Array
6	Check the expression has valid or Balanced parenthesis or not.
7	Reverse a String using Stack
8	Design a Stack that supports getMin() in O(1) time and O(1) extra space.
9	Find the next Greater element
10	The celebrity Problem
11	Arithmetic Expression evaluation
12	Evaluation of Postfix expression
13	Implement a method to insert an element at its bottom without using any other data structure.
14	Reverse a stack using recursion
15	Sort a Stack using recursion
16	Merge Overlapping Intervals
17	Largest rectangular Area in Histogram
18	Length of the Longest Valid Substring
19	Expression contains redundant bracket or not
20	Implement Stack using Queue
21	Implement Stack using Deque
22	Stack Permutations (Check if an array is stack permutation of other)
23	Implement Queue using Stack
24	Implement "n" queue in an array
25	Implement a Circular queue
26	LRU Cache Implementationa
27	Reverse a Queue using recursion
28	Reverse the first “K” elements of a queue
29	Interleave the first half of the queue with second half
30	Find the first circular tour that visits all Petrol Pumps
31	Minimum time required to rot all oranges
32	Distance of nearest cell having 1 in a binary matrix
33	First negative integer in every window of size “k”
34	Check if all levels of two trees are anagrams or not.
35	Sum of minimum and maximum elements of all subarrays of size “k”.
36	Minimum sum of squares of character counts in a given string after removing “k” characters.
37	Queue based approach or first non-repeating character in a stream.
38	Next Smaller Element