1. TUTORIAL 9
CS 137 F18
November 13th

2. Overview
a6 Common Mistakes
a7 Progress
a8 Hints
Big Oh Practice

3. a6 Common Mistakes a6p1: euclidean_algorithm.c a6p2: run.c
Divide by zero
a6p2: run.c
Printing the final character
a6p3: merge.c
Overall very well done
sort immediately

4. a7 Progress? Questions? A7p2: num_duplicates.c A7p3: largest_square.c
Add a case for the NULL string!
Array type makes sense
A7p3: largest_square.c
Easy to find a square
Trouble finding the largest

5. a8 Hints Questions? MUST remove main function (comment or delete)
Start as soon as it is covered in lecture
a8p1: multipleChoice.c
Taking the most recent submission
a8p2: insert_or_merge.c
Use print statements; remove them before you submit
Can change anything besides the problem’s function inputs; do not go crazy
a7p3: sum_to_zero.c
Use an efficient sort AND an efficient comparison; no nested for loops
Stress test case topic

6. Big O Notation Most efficient O(1) Constant time O(log(n))
a means for measuring the time efficiency of an algorithm based on the number of inputs, n
Most efficient
O(1)
Constant time
O(log(n))
Logarithmic time
O(n)
Linear time
O(n*log(n))
Linearithmic time
O(n2)
Quadratic time
O(nc) (c > 2)
Polynomial time
O(cn) (c > 1)
Exponential time
Least efficient
O(n!)
Factorial time

8. Which of the following is ordered correctly from most efficient to least?
A) O(1), O(logn), O(n), O(nlogn), O(n4), O(nn), O(cn), O(n!)
B) O(1), O(nlogn), O(n), O(logn), O(n4), O(cn), O(n!), O(nn)
C) O(1), O(logn), O(n), O(nlogn), O(n4), O(cn), O(n!), O(nn)
D) O(nn), O(n!), O(cn), O(n4), O(logn), O(n), O(nlogn), O(1)
E) None of the Above

9. 26 is O(1)
A) True
B) False

10. 53n2 + 2n3 + 4n is O(n2)
A) True
B) False

11. n + log(n) is O(n)
A) True
B) False

12. 2n + n100 is O(2100)
A) True
B) False

13. 4n4 + 2n2 is: A) O(n2) B) O(n4) C) O(en) D) All of the Above.
E) Only B and C

14. 9n*log(n) + 5n2 is O(n*log(n))
A) True
B) False

15. n2 + 3n5 + 5n + 4n3 + 2 is O(2n)
A) True
B) False

16. n2 + 3n5 + 5n + 4n3 + 2 is O(1n)
A) True
B) False

17. Examples see examplesBigOh.zip
Set your clicker back to classroom’s ID: BD