Data structures worksheet with answers

What is the name of the queue operation that removes the element at the front?

1. ADequeue
2. BInsert
3. CPush
4. DEnqueue

Which data structure works on the principle "first in, first out"?

1. AStack
2. BQueue
3. CBinary tree
4. DHeap

A graph consists of:

1. AOnly a root and leaves
2. BVertices (nodes) connected by edges
3. CKeys and hashes only
4. DRows and columns

How is a new element inserted into a binary heap?

1. AInsert it at its sorted position by shifting all of the larger elements one place right
2. BPlace it at the end of the array and sift it up while it violates the heap property
3. CRebuild the whole heap from scratch
4. DPlace it at the root and sift it down

What is the time complexity of searching for a key in a balanced binary search tree?

1. AO(n log n)
2. BO(1)
3. CO(log n)
4. DO(n)

What is the cost of inserting an element in the middle of an array of n elements?

1. AO(log n), because of binary search
2. BO(n), because later elements must shift
3. CO(1), because the index is known
4. DO(n²), because each element moves n times

Which data structure supports an LRU (least recently used) cache with O(1) get and put?

1. AA binary search tree only
2. BA stack only
3. CA hash map combined with a doubly linked list
4. DA single sorted array

Which property keeps every B-tree perfectly balanced?

1. AAll leaves are at the same depth
2. BEvery node has exactly two children
3. CEach node stores one key
4. DThe keys are stored only in the root