Am I Prepared for CSCI-E26?

CSCI-E26 assumes students have a certain level of programming experience and knowledge. The course is an introduction to C/Unix and CGI, but it is not an introduction to programming.

There is no sure way to predict if the level and speed of the course will be too quick for you, but here are some problems to try. Write the solutions in any language you like. If you have trouble solving, coding, or getting working solutions to these problems, you should consider taking a more introductory programming class.

Note about AI: If you need to use AI to do these ...

then you will be better off in an introductory programming course. If you want an explanation of why I expect/want students to know how to program on their own, please write or call me: Bruce Molay, molay@fas.harvard.edu, 617-864-8832 immediately. This is very important. And is not a joke. I really want to hear your thoughts, and I really want to talk to you. The more all of us can understand AI, education, and the human brain, the better.

The Problems

1. Write a program to read in a list of non-zero integers. The user inputs a zero to indicate end of input. The program then prints the average of all the numbers and the difference between the largest number and the smallest number entered. There should be no maximum number of integers in the list. Do not use built-in max, min, or average functions.

2. Write a program that finds the number of days between two dates in the same year. The user inputs one date, presses the return key, then enters another date. The input is of the form "Month day", for example, Jul 4 or Oct 31.
   Do not use built-in date parsing functions. Write the algorithm yourself.

3. Write a prgram that prints out a diamond shape made of alternating #'s and _'s that looks like:

                          #
                         #_#
                        #_#_#
                         #_#
                          #
   	

   Your program should accept a positive integer as input and print a checkerboard diamond with that many rows. In the example shown, the number of rows is five. Your program should work for even and odd numbers.

4. Write a program that sorts the words in a text file. In particular, the file contains one word per line. The user specifies the name of the file containing the words and the name of a file to put the result. The program reads the words from the input file and writes the sorted list into the output file. You have to code a sorting algorithm; using a built-in sort operation for a language is not ok for this problem. You may use any sorting algorithm; you do not have to devise a new one.

5. Write a program that reads an arbitrary amount of text from a file or from the keyboard and reports how many a's, b's, c's, d's, ... z's are in the text. The program should ignore whether the letter is upper case or lower case.

   version 2 Modify the program so the output lists the letters and the number of times each appears in frequency order: most frequent first, least frequent last.