Stacks & Queues Problems

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Arrays Strings 2D Arrays Searching & Sorting Backtracking Linked List Stacks & Queues Greedy Binary Trees Binary Search Trees Heaps & Hashing Graphs Tries DP Bit Manipulation Segment Trees

1

Implement two stacks in an Array

Easy

2

Evaluation of Postfix Expression

Easy

3

Implement Stack using Queues

Easy

4

Queue Reversal

Easy

5

Implement Stack Queue using Deque

Easy

6

Reverse first k elements of queue

Easy

7

Design Stack with Middle Operation

Medium

8

Infix to Postfix

Medium

9

Design and Implement Special stack

Medium

10

Longest Valid String

Medium

11

Find if an expression has duplicate parenthesis or not

Medium

12

Stack permutations check if an array is stack permutation of other

Medium

13

Count natural numbers whose permutation greater number

Medium

14

Sort a stack using Recursion

Medium

15

Queue based approach for first non repeating character in a stream

Medium

16

The Celebrity Problem

Medium

17

Next larger Element

Medium

18

Distance of nearest cell

Medium

19

Rotten-oranges

Medium

20

Next smaller element

Medium

21

Circular-tour

Medium

22

Efficiently implement k-stacks single array

Hard

23

The celebrity problem

Hard

24

Iterative tower of hanoi

Hard

25

Find the maximum of minimums for every window size in a given array

Hard

26

lru cache implementation

Hard

27

Find a tour that visits all stations

Hard