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GK One-Line Question & Answer

15541+ short questions with short answers, covering every category and sub-category on the site — no long articles to scroll through. Good for a fast recap before an exam, or a few minutes of daily practice.

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Data Structures and Algorithms → Queue 14

Array-based queue is full when?
Q.head==Q.tail+1
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Queue using linked list IS_EMPTY checks?
Q.head==null
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What is a priority queue?
Each element has priority; higher served first
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Two types of priority queues are?
Min and Max priority queue
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In enqueue of linked list queue when empty?
New node both head and tail
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DEQUEUE in linked list: head becomes?
Q.head=Q.head.next
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Time complexity of enqueue and dequeue in linked list queue?
O(1)
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What is a deque?
Both front and rear insertion/deletion
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Initial head and tail in array queue class?
1
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After enqueue(10,20,30,40,50), dequeue(), dequeue() — remaining?
30,40,50
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During dequeue in linked list, which node is deleted?
Head (old front)
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Which algorithm uses queue for level-order traversal?
BFS/Level-order
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Priority queue most efficiently implemented with?
Binary Heap O(log n)
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Circular queue IS_FULL when?
head==tail+1
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Data Structures and Algorithms → Graphs 1

BFS uses which data structure?
Queue
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Data Structures and Algorithms → Introduction to DSA 13

Real-world example of queue?
Movie ticket queue (FIFO)
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OS job scheduling with equal priority uses?
Queue
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FRONT operation in queue:
Returns front without removing
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Printer spooling uses which data structure?
Queue
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Call center uses which structure to hold waiting customers?
Queue
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Minimum queues needed to implement a stack?
2
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What does 'head' pointer point to?
First element
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In doubly LL addNode(), when list is empty?
Both head and tail point to new node
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What is self.tail.next set to after adding node at end of doubly LL?
NULL/None
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In circular LL add() when empty, newNode.next=?
newNode itself
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Circular LL display() while loop stops when?
current.next!=self.head
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Doubly LL display() after adding 1,2,3,4,5?
1 2 3 4 5
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Circular LL advantage over singly LL?
Traverse entire list from any node
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Data Structures and Algorithms → Linked List 12

Two parts of a node in singly linked list?
data and next pointer
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Last node's 'next' in singly linked list points to?
NULL
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Advantage of linked list over arrays?
Dynamic size — no resizing needed
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Doubly linked list node has how many fields?
Three (prev, data, next)
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Advantage of doubly over singly linked list?
Traversal in both directions
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Disadvantage of doubly over singly linked list?
Extra pointer increases memory
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Circular linked list: tail node's 'next' points to?
Head node
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Previous pointer of head node in doubly linked list?
Points to None/NULL
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Next pointer of tail node in doubly linked list?
Points to None/NULL
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Time complexity of accessing element at index n in linked list?
O(n)
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Time complexity of insertion at head of linked list?
O(1)
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Best linked list for browser back-forward navigation?
Doubly
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