[Tutor] Complications Take Two (Long) Frustrations.

[Joseph Gulizia]

Complicating a simple expression

Coding Exercise: Complication

Assume that the grader defines two variables A and B for you. Write a
program which prints out the value
min(A, B)

However, there is a catch: your program is not allowed to use the min
function. Instead, use max in a clever way to simulate min.

Hint, Method 1
What is max(-A, -B)?

Hint, Method 2
What is min(A, B)+max(A, B)?
--------------------------------------
Code that gave best results but didn't work for negative numbers...
--------------------------------------

Original = abs(max (-A, -B))
print (Original)

--------------------------------------
Did not pass tests. Please check details below and try again.
Results for test case 1 out of 5
Before running your code: We defined A equal to 35 and B equal to 45.

Program executed without crashing.
Program gave the following correct output:

35

Results for test case 2 out of 5
Before running your code: We defined A equal to 65 and B equal to 20.

Program executed without crashing.
Program gave the following correct output:

20

Results for test case 3 out of 5
Before running your code: We defined A equal to 48 and B equal to 63.

Program executed without crashing.
Program gave the following correct output:

48

Results for test case 4 out of 5
Before running your code: We defined A equal to 0 and B equal to 70.

Program executed without crashing.
Program gave the following correct output:

0

Results for test case 5 out of 5
Before running your code: We defined A equal to -64 and B equal to 0.

Program executed without crashing.
Program output:

64

Expected this correct output:

-64

Result of grading: Your output is not correct.


Spreadsheet examples:


  A       B        Min(A, B)        Max(-A,- B)

 10         5            5            -   5
   5       10            5            -   5
   9       12            9            -   9
 12         9            9            -   9
 22       37           22            - 22
 37       22           22            - 22
 45       68           45            - 45
 68       45           45            - 45
-  6       15        -   6                6
-15         6        -  15              15
-80    -  65        -  80              80
-65    -  80        -  80              80
 44    -102        -102             102
-44     102        -  44               44


CS Assistant2 stated:

Using the absolute value of the numbers will cause problems with this
solution because sometimes the answer should be a negative number. However,
when you calculate the absolute value of a number, that result will always
be larger than any negative number.

I would suggest you go back to your original table, but include some values
for A and B that are negative numbers (A is negative, B is negative, A and
B are both negative). See what numbers you get for min(A, B) and max(-A,
-B) in those cases.

Think about ways, other than absolute value, that will allow you to convert
a negative number to a positive number and vice versa.

I hope this helps.

Sandy



CS Assistant1 stated:

Hi,

Gathering this much data is a very good start! The two hints give two
different approaches. So let me highlight the 4 most relevant columns:

A       B    Min(A, B)    Max(-A,- B)
10      5              5          -5
  5    10              5          -5
  9    12              9          -9
12      9              9          -9
22    37            22         -22
37    22            22         -22
45    68            45         -45
68    45            45         -45

What's the relationship between min(a, b), which you want but can't
directly call, and max(-a, -b), which you can compute? Feel free to ask if
another hint would help.

Best,
- Dave