CSE 2050 Exam 2
Write a O(n) contains function with one line of code - ANS-return any(obj == item for i in
L)
What is the run time of binary search with slicing? - ANS-O(nlogn)
What is the run time of binary search with reference? - ANS-O(logn)
Why is iteration better than recursion? - ANS-Iteration is generally faster and takes less
memory space
Dynamic Programming - ANS-Sub-problems are solved from the bottom up. Each
problem is trivially solved as the combination of previously-solved subproblems.
Greedy Algorithm - ANS-an algorithm that always tries the solution path that appears to
be the best.
Memoization - ANS-Before attempting to solve a new sub-problem, a collection is
referenced to see if this sub-problem has already been solved.
Drawbacks of Recursion - ANS-Can be slow, take a lot of memory space, can solve the
same subproblems repeatedly
Recursion can help (?) - ANS-Explore branching paths
Recursion - ANS-the process of calling the function by itself until it reaches a base case
Binary Search - ANS-An ordered list is divided in 2 with each comparison.
Prune and Search - ANS-method for finding an optimal value by iteratively dividing a
search space into two parts
Invariant - ANS-something that holds true throughout the execution of a code
Invariant for Bubble Sort - ANS-The biggest items of the list are in their sorted, final
position after each loop
, Invariant for Selection Sort - ANS-Same thing with Bubble Sort, where the biggest items
of the list are in their sorted, final position after each loop
Invariant for Insertion Sort - ANS-After each loop, a small portion of the list, or sub list,
are sorted, but does not mean that each element are in their final position
Best and Worst Case for Bubble Sort - ANS-Best Case: if only one item (particularly the
rabbit) is unsorted, O(n)
Worst Case: O(n^2), has to go through every item (reversed sorted list, turtle,
randomized)
Best and Worse Case for Selection Sort - ANS-Best Case: reverse sorted, though
O(n^2), randomized sometimes
Worst Case: if just one object are out of places
Benefit of Using Selection Sort - ANS-It only makes one swap per element (O(n)), which
can reduce memory cost
Best and Worst Case for Insertion Sort - ANS-Best Case: only one object out of place
O(n) swap
Worst Case: reversed sorted (O(n^2))
Compare Insertion Sort vs Selection Sort (3) - ANS-1) Number of comparisons is less
than number of swaps in insertion
2) Insertion is generally more efficient
3) O(n) swaps in selection vs O(n^2) swaps in insertion
Why is Binary Search O(logn) - ANS-Every iteration is n/2^k, and after k divisions, the
length of the list will equal to 1. As a result, 1 = n/2^k, 2^k = n, which log2n = k.
Best Case for Binary Search - ANS-O(1), if median happens to be the item
Rank the O(n^2) (from best to worst) in a randomly distributed list - ANS-Insertion sort,
Selection Sort, Bubble Sort
Rank the O(n^2) if one item is out of place (also explain why Bubble performs bad when
it handles turtle) - ANS-Insertion, Bubble, Selection
Rank the O(n^2) if list is reversed sorted - ANS-Selection, Insertion, Bubble
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