Top 50 Problems on Queue Data Structure asked in SDE Interviews
Last Updated :
20 Feb, 2025
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A Queue is defined as a linear data structure that is open at both ends and the operations are performed in First In First Out (FIFO) order. We define a queue to be a list in which all additions to the list are made at one end, and all deletions from the list are made at the other end. The element which is first pushed into the order, the operation is first performed on that.
To learn more about Queue, please refer to the Tutorial on Queue.
Easy Problems
- Reverse First k Elements of Queue
- Implement a Queue using an Array
- Print all elements of a queue in a new line
- Level with maximum number of nodes
- Breadth First Search or BFS for a Graph
- Find Minimum Depth of a Binary Tree
Medium Problems
- Implement a Deque
- Implement a Circular Queue
- Check if a queue can be sorted into another queue using a stack
- Implement Stack using Queues
- Implement Stack using Two Queues
- Implement Queue using Two Stacks
- Design a Queue data structure to get minimum or maximum in O(1) time
- Check whether a given graph is Bipartite or not
- Print Right View of a Binary Tree
- An Interesting Method to Generate Binary Numbers from 1 to n
- Implement a Queue using a Stack
- Reverse a queue using recursion
- Implement Priority Queue using Linked List
- Implement Queue using Deque
- Flatten a multilevel linked list
- Find next right node of a given key
- Detect cycle in an undirected graph using BFS
- Minimum steps to reach target by a Knight
- Islands in a graph using BFS
- Flood Fill Algorithm
- Minimum steps to reach target by a Knight
- First negative integer in every window of size k
- Level order traversal in spiral form
- Minimum time required to rot all oranges
- Queue based approach or first non-repeating character in a stream
- Shortest distance in a maze
- Geek in a Maze
- Find shortest safe route in a path with landmines
- Find the first circular tour that visits all petrol pumps
- Connect Nodes at Same Level
Hard Problems
- Find the first non-repeating character from a stream of characters
- Maximum of all subarrays of size k using a queue
- Implement LRU Cache using Queue
- Design a Queue data structure to get the maximum or minimum of sliding window
- Find if there is a path between two vertices in a directed graph
- Design a Data Structure for LRU Cache
- Trapping Rain Water
- Maximum cost path from source node to destination
- Trapping Rain Water
- Maximum cost path from source node to destination
- Snake and Ladder Problem
- Minimum Cost Path in a directed graph via given set of intermediate nodes
- Turn a Queue into a Priority Queue
- Interchange elements of Stack and Queue without changing order
