代写Python基础作业，练习loops的使用。
Introduction
For this assignment you will write three short programs.
Reminder
If you talk to someone else (besides the professor) about the assignment, you
need to cite this collaboration. If you use any external resources besides
class notes and the book, you also need to cite it.
Preliminaries
Log in to gemini and enter these commands to start the project:
cs110
start loops
cd ~/110/loops
This will copy 3 “skeleton programs” to your account. Use the first and third
commands above to start each work session. Do not run “start loops” more than
once; if you do, it will replace any programs you have written with new blank
programs.
Part 1
Filename: ~/110/loops/alphabet.py
The alphabet game is a game played on long car trips, in which the occupants
of the car try to find every letter of the alphabet on signs outside of the
car. As an adaptation of this game, your task is to write a program that,
given a string of text from the user, tells which letters in the alphabet do
not appear in the string. Your program should consider both uppercase and
lowercase letters to qualify as a letter in the string; in other words, both
“A” and “a” as the letter A in the string. Your program should print, in
alphabetical order, the uppercase version of the letters that do not appear in
the input.
Here is a sample interaction with the program. Bold/underlined values indicate
user input.
Enter some text: The quick brown fox ate 4 rotten eggs and said “YUCK!”
Letters not in the text: JLMPVZ
Part 2
Filename: ~/110/loops/ball.py
A standard science experiment is to drop a ball and see how high it bounces.
Once the “bounciness” of the ball has been determined, the ratio gives a
bounciness index. For example, if a ball dropped from a height of 10 feet
bounces 6 feet high, the index is 0.6 and the total distance traveled by the
ball is 16 feet after one bounce. If the ball were to continue bouncing, the
distance after two bounces would be: 10 ft + 6 ft + 6 ft + 3.6 ft = 25.6 ft
note that the ball traveled 16 feet on the first bounce, and 9.6 feet on the
second bounce.
Note that distance traveled for each successive bounce is the distance to the
floor plus 0.6 of that distance as the ball comes back up. Write a program
that lets the user enter the initial height of the ball (10 in this example),
its height after the first bounce (6 in this example), and the number of
bounces. Output should be the total distance traveled by the ball, rounded to
at most 2 decimal places.
Here is a sample interaction with the program:
Enter initial height: 10
Enter height of first bounce: 6
Enter number of bounces: 2
The total distance the ball traveled is 25.6 feet.
Here is another run:
Enter initial height: 20.4
Enter height of first bounce: 9.22
Enter number of bounces: 11
The total distance the ball traveled is 54.04 feet.
Part 3 Filename
~/110/loops/microwave.py
Imagine you are using the timer on a microwave. You enter the time you want to
count down from, in minutes and seconds, and the microwave counts down until
it reaches 0:00. Your program will, given the minutes and seconds to count
down, print the times remaining displayed by the microwave while the timer
counts down, with one time on each line. Note: Your program shouldn’t actually
take a second between printing each line.
Here is a sample interaction with this program:
Enter the digits as input to the microwave:
0:11
0:11
0:10
0:09
0:08
0:07
0:06
0:05
0:04
0:03
0:02
0:01
0:00
Here is another run of his program (trimmed in the middle for length):
Enter the digits as input to the microwave: 10:03
10:03
10:02
10:01
10:00
9:59
9:58
9:57
…
0:03
0:02
0:01
0:00
And a third example (note that microwaves usually allow you to enter more than
60 seconds):
Enter the digits as input to the microwave: 0:95
0:95
0:94
0:93
0:92
…
0:03
0:02
0:01
0:00
What to hand in Submit your work using the course submission procedure. In
this case it is
cd ~/110/loops
submit loops
This will collect the three files: alphabet.py, ball.py, and microwave.py.
Evaluation criteria
Your work will be evaluated according to criteria in two general categories,
style and correctness. Each category counts for half of your grade. For this
assignment, the criteria are:
- Style
* The header (large docstring at the top) contains all the appropriate information: your name, the name of the file, etc; and that the program description is accurate and complete,
* The logic (approach to solving the problem) is clear and reasonably simple,
* Variable names are descriptive, that is, they accurately describe the values they name,
* Commenting is accurate and complete, and
* The horizontal and vertical spacing effectively enhances the structure of the program.
* The program is efficient and avoids redundant computations. If the same calculation is used twice, it is better to do it once and store the result in a variable.
* No variables are unnecessary. A rule-of-thumb is that a variable is necessary only when it names an important part of the logic, or when it is used in the logic more than once after it is assigned. - Correctness
* The submission system will evaluate how well your program passes the automatic tests.
