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Data Structures
Interview Questions
C++ Data Structure Runtimes
Data Structure
Insert
Find
Delete
vector
O(n)
O(1) amortized
O(n)
O(1) if index is known
O(n)
sorted vector
O(n)
O(log(n))
O(n)
linked list
(list, stack, queue)
O(1)
*Given an Iterator
O(n)
O(1)
*Given an Iterator
balanced binary tree
(map, set)
O(log(n))
O(log(n))
O(log(n))
hash table
(unordered_set,
unordered_map)
O(1)
O(1)
O(1)
Heap
(priority_queue)
O(log(n))
N/A
O(1) to find min
O(log(n))
Common Interview Questions
• *These types of questions will not be on the
final exam
• Find the middle element of a linked list in one
pass.
• What if the list has a cycle?
• Detect a cycle in a linked list.
Common Interview Questions
• *These types of questions will not be on the
final exam
• Given an array of size 100 containing one copy
each of the integers 1-100 with exactly one
integer being repeated once, find the
repeated integer.
• Given an array of arbitrary integers, find all
integers that appear exactly twice.
Common Interview Questions
• *These types of questions will not be on the
final exam
• Implement a stack that can also give the
minimum element in the stack at any given
time. push, pop, and min must all run in O(1)
time.
Common Interview Questions
• *These types of questions will not be on the
final exam
• In class we described a stack that was
implemented as a linked list. How could we
implement a stack as a vector?
• How could we use a single vector to
implement 3 stacks?
Common Interview Questions
• *These types of questions will not be on the
final exam
• Give a function that will sort a vector of string
such that all the anagrams are next to each
other, ignoring spaces.
– Two words are anagrams of each other if they use
exactly the same letters
– ex. “interpreter” and “enter err pit”