CSC 127A Lecture Notes - Lecture 19: Filename Extension, Skip List

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sapphirewombat829

8 Oct 2016

School

University of Arizona

Department

Computer Science Main

Course

CSC 127A

Professor

Allison Obourn

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Document Summary

Functions should not call other functions over and over again, they should return to main, and maybe call one other function before returning back to the main function. Every time you change an aspect to your program, be sure to run your program to make sure that it still runs. If it does not, you can easily identify which part broke your program. It is now okay to use small functions in main, and an occasional print statement. File output: name. write(str) = will write the given string to the file name. close() = will close the file, make sure to do this step. Do not open ( guessing_game. py , w ) this will open the file, delete your already made code, and write over your code. For the next homework assignment, save the write file in a different directory to reduce the chance of writing over a file.

Related Questions

Given the following main program

#main
a = [5,2,9,6,3] doubleList(a) print a

Implement the function named doubleList that takes one list argument and modifies the list so that each element in the list is doubled. The statement print(a) in the main program will then have to print [10,4,18,12,6]
Given the following main program

#main
a = [5,2,9,6,3]
b = reversedList(a) print b
print a

Implement the function named reversedList that takes one list argument and returns a list that contains the elements in the list argument in reverse order. The statement print(b) in the main program will then have to print [3,6,9,2,5]. The statement print(a) must print the original list [5,2,9,6,3] unaffected. This means your function should not modify the list argument.
Given the following main program

#main
a = [5,2,9,6,3] reverseList(a) print a

Implement the function named reverseList that takes one list argument and reverses the list so that the modified list contains the same elements in reverse order. The statement print(a) in the main program will then have to print [3,6,9,2,5]
What is the return value of the functions doubleList, reversedList and reverseList in questions 1, 2, and 3 above?

Given the following main program

#main
a = [5,2,9,6,3]
b = evenElements(a) print b

Implement the function named evenElements that takes one list argument and returns a list that contains the elements in the list argument that are even integers. The statement print(b) in the main program will then have to print [2,6]. What is the return value of the function? Your function should not modify the list argument.
Given the following main program

#main
a = [5, 2, 9, 6, 3, 7, 19, 4, 8, 17, 21, 20, 15] removeOddElements(a)
print a

Implement the function named removeOddElements that takes one list argument and modifies the list so that all odd integers in the list are removed. The statement print(a) in the main program will then have to print [2,6,4,8,20]. What is the return value of the function?
Part A
#Main program A=[5,8,2,0,-5,3] n=-5
answer = isFound(A, n) if answer == True:

print "The integer is found in the list" else:

print "The integer is not found in the list."

Consider the main program shown above. Write a Python function named isFound that takes a list of integers and an integer as arguments and returns True if the integer is found in the list; otherwise it returns False.

Remark: You are NOT allowed to use the in operator or any other built in function when you write this function. Instead, you must write a loop to go through the elements of the list.

Part B

Give the following main program

#main
A = [5,2,9,6,3]
B = [2,4,3,9,7,1,6,5]
flag = isList1InList2(A, B) if flag:

print "The list", A, "is contained in the list", B else:

print "The list", A, "is not contained in the list", B

Implement the function named isList1InList2 that takes two list arguments and returns True if and only if each element of the first list argument are found in the second list argument; otherwise it returns False.

Remark: You are NOT allowed to use the in operator or any other built in function when you write this function. Instead, if you wish, you can use the function you wrote in Part A.

For the lists shown in the main program, your function must return True because each element of list A is found in list B.

A given List is known as Palindrome List if the reverse of the List contains the same elements in the same order of the original List. For example the List of integers [2, 5, 0, 3, 3, 0, 5, 2] is a Palindrome because the reverse of the List which is [2, 5, 0, 3, 3, 0, 5, 2] contains the same elements in the same order as the given List. However the List [1, 2, '2', 1] is not Palindrome because its reverse which is [1, '2', 2, 1] does not contain the same elements in the same order as the given List.

Write a Python function named isPalindrome that takes a List as argument and returns True if the argument is a Palindrome List; otherwise it returns False. You don't need to write the main program; just write the function. If you would like to test your function, then it is ok to write the main program too but you will not get any mark for the main program.
Given your function in question #7 above, what is the output of the following code: a=[]

b = [5,2,9,6,3]

print isList1InList2(a,b)
Given your function in question #7 above, what is the output of the following code:

a=[]
b=[]
print isList1InList2(a,b)
Given your function in question #7 above, what is the output of the following code: a = [5,2,9,6,3]

b=[]

print isList1InList2(a,b)

Given the following main program

#main
a=[]
n = readListElements(a)
print "The user entered", n, "elements to the list" print a

Implement the function named readListElements that takes one list argument and modifies the list by repeatedly asking the user to enter integer values and then appending them to the list. The process stops when the user enters -1000. The stopping value -1000 should not be appended to the list. Moreover your function must count the appended elements and return it. Example if the user enters the integers 31, -4, 9, 1,-1000 then your function must modify the list a to a = [31, -4, 9, 1] and return the number elements added which is 4.
Write a function named createRandomList that takes an integer argument n and returns a list with n elements. The elements must be random numbers in the range [0,100]

Given the following main program:

#main

   n = int(input("How many elements do you want in your list? "))
   a = createList(n)
   s1 = sumOfElementsAtEvenIndexes(a)
   print s1

   s2 = sumOfElementsAtOddIndexes(a)
   print s2
   s3 = sumOfAllElements1(a)
   print s3

   s4 = sumOfEvenElements(a)
   print s4
   s5 = sumOfOddElements(a)
   print s5

   s6 = sumOfAllElements2(a)
   print s6
   if (s3 != s6):

         print "Something is wrong in your program."
   else:

         print "Looks like you have done a good job."

Implement the functions as follows:

createList: returns a list object with n elements. The elements are generated randomly so that each element is in the range [15,45]
sumOfElementsAtEvenIndexes: returns the sum of the elements at even indexes. Use a for loop or a while loop.
sumOfElementsAtOddIndexes: returns the sum of the elements at odd indexes. Use a for loop or a while loop.
sumOfAllElements_A: returns the sum of all the elements in the list using the functionssumOfElementsAtEvenIndexes and sumOfElementsAtOddIndexes. Here you are NOT allowed to use any loop; instead make function calls as described.
sumOfEvenElements: returns the sum of the even integer elements in the list. Use a for loop or a while loop.
sumOfOddElements: returns the sum of the odd integer elements in the list. Use a for loop or a while loop.
sumOfAllElementsB: returns the sum of all the elements in the list using the functions sumOfEvenElements and sumOfOddElements. Here you are NOT allowed to use any loop; instead make function calls as described.

17. Most data compression algorithms like winzip, gzip, lzip and etc are based on the frequency distribution of characters in a given string. Write a function named getFreqDistribution that takes a string argument and returns a LIST that has length 26 such that the first element of the list is the number of appearance of 'a' or 'A' in the string, the second element is number of appearance of 'b' or 'B', and so on so forth.

I'm studying python 2 and have a lot of troubles with solving these homework questions.

grayelk171

9. Finally, you should write a program MontrealMaps which will suggest a path to go along the metro to get from one place to another. The only required method for MontrealMaps is a main method but of course you are allowed to write others. Your program should do the following. For any library methods that you use, make sure that you are properly importing things and handling any exceptions they may throw. (10 points) • Using an appropriate library method, you should create a Subway System object. If this method fails to initialize, you should print the message Error, not enough funding. • Use a Scanner and print statements to read the current x and y position of the user. • Use a Scanner and print statements to read the x and y position that the user wants to go to. . Find the nearest Metro Station to both the start position of the user and his final destination. • If the 2 metro stations have the same name (i.e. are the same metro station) then print It is fastest to walk there. • Otherwise, call the method findPath from the previous part to find a path from these 2 metro stations. . If the method returns null, then print Sorry, there is no path on the metro, you'll have to walk • Otherwise, print the path using the metro using the method printPath defined in the MapUtilities class in the appendix. SUMMARY OF JAVA STANDARD LIBRARY METHODS POR SELECTED CLASSES • String package java.lang) Methods - public boolean gist and e rs is stingeancoject - puble boolean grease Sering another ca t ering String paint i th Stre C h eshilly before the Stripe with striert w Single weiter water N ENE fusha -publish tohy Casting de . File( p age java.io) Methods r eate - publie Yiling path : C • Scanner (package java.ut 1) Method -ple S ule - double Double Sc - le bon when : S Scanner tal de fethede h able othebean - puble String Best Mus eethe u s tepal -pulle haalean haxtLine: Check the hea ther in left PrintStream( p age java.io) Methods pul vaid pri Pribonaat - puli wid pride d oble vile. - pille vaid print Print vei. -pulle vaid printject o: Prints Object -puli vaid printString : Prints String .. - vaid primi The theme line by writing the li n e tie id print in bool bl. Prise n value the - public void platinabled Prints double ved and then the line - public void printit Prints Ent value and then tomis the - Pull vaid pri l l be t he minime publie wild prin t ing with String in the terminates the line • ArrayLiat package java.util) Methods - public boolean Arraybettype was a new ArrayList

CSC 127A Lecture Notes - Lecture 19: Filename Extension, Skip List

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