Description
1. Write a program called hw2_1.cpp (or hw2_1.java) that reads two timestamps of two events from a
user and displays the difference between the two timestamps. For the program, you can assume that each
timestamp is composed of the hour (0 ~ 23), minute (0 ~ 59), and second (0 ~ 59) format. Your program
should present the difference from the second event (= second timestamp) to the first event (= first
timestamp). Note that the second event always happens after the first event and your program should
display the time difference of the events.
Sample Run 0: Assume that the user typed the following two lines.
18:45:30
20:50:59
This is the correct output of your program.
02:05:29
Sample Run 1: Assume that the user typed the following two lines.
20:18:59
04:25:17
This is the correct output of your program.
08:06:18
Sample Run 2: Assume that the user typed the following two lines.
02:00:25
15:30:00
CST370 Page 1 of 4 Homework 2
This is the correct output of your program.
13:29:35
2. Write a C++ program called hw2_2.cpp (or hw2_2.java) that reads a number of elements in a set first.
Then, your program should read the elements of the set. After that, your program should display all
possible decimal numbers, corresponding binary numbers, and subsets one by one. For the program, you
can assume that the number of elements in a set is less than 10.
Sample Run 0: Assume that the user typed the following input. Note that there are three elements in the
set with the elements A, B, and C.
3
A B C
This is the correct output.
0:000:EMPTY
1:001:C
2:010:B
3:011:B C
4:100:A
5:101:A C
6:110:A B
7:111:A B C
The first line indicates that the first decimal number and its binary number are “0” and “000”. Note that
the first bit ‘0’ in the binary number is for the element ‘A’, the second bit ‘0’ for the element B, and the
last bit ‘0’ for the element C. Since all three bits in the binary number are ‘0’, the corresponding subset is
“EMPTY”.
The next line indicates that the second decimal number and its binary number are “1” and “001”. The
corresponding subset is {C} because only the last bit of the binary number is ‘1’.
This way, your program should display a decimal number, its binary number, and corresponding subset
one by one. For instance, the last line indicates that the last decimal number and its binary number are “7”
and “111”. The corresponding subset is {A, B, C} because all bits of the binary number are ‘1’.
Sample Run 1: Assume that the user typed the following input.
2
CST238 CST370
This is the correct output.
0:00:EMPTY
1:01:CST370
2:10:CST238
3:11:CST238 CST370
CST370 Page 2 of 4 Homework 2
Sample Run 2: Assume that the user typed the following input.
0
This is the correct output of your program.
0:0:EMPTY
[Hint]: Refer to this program to convert a decimal number to corresponding binary number –
https://www.geeksforgeeks.org/program-decimal-binary-conversion/
3. Write a C++ (or Java) program named hw2_3.cpp (or hw2_3.java) which checks if an input string is a
palindrome or not. In the problem, a palindrome means an alphanumeric string which reads the same
front to back. For the problem, you should ignore case and remove all non-alphanumeric characters in the
input string. For example, “Race car”, “I did, did I?”, “7…8 Don’t nod 87.” are all palindromes. But
“CSUMB” is not a palindrome.
In this program, you have to use a recursive function to check the palindrome. For the grading, we
will read your source code. If you do not use a recursive function, you will get zero even if your
program passes all test cases.
Sample Run 0: Assume that the user typed the following one line
Race car
This is the correct output of your program.
TRUE
Sample Run 1: Assume that the user typed the following one line
7…8 Don’t nod 78.
This is the correct output of your program.
FALSE
Sample Run 2: Assume that the user typed the following one line
7 77 777 7777 UFO tofu? 7777777777
CST370 Page 3 of 4 Homework 2
This is the correct output of your program.
TRUE
[Hint] First, convert the input string to a string with only alphanumeric characters in uppercase. After
that, check if the converted string is a palindrome or not using a recursive function.
CST370 Page 4 of 4 Homework 2
