Computer Networking: A Top-Down Approach (7th Edition)
7th Edition
ISBN: 9780133594140
Author: James Kurose, Keith Ross
Publisher: PEARSON
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I need some help making this code more simple.
2)
tokenList = "{}()[]"
initialize stack to empty
Get file name from user: fileName
Open the file (fileName)
read line from fileName into strLine
while not EOF (end of file)
find tokenList items in strLine
for each token in strLine
if token = "[" then
push "]" into stack
else if token = "(" then
push ")" into stack
else if token = "{" then
push "}" into stack
else if token = "]" OR token = ")" OR token = "}" then
pop stack into poppedToken
if poppedToken not equal token
print "Incorrect Grouping Pairs"
exit
end if
end if
next token
end while
if stack is empty
print "Correct Grouping Pairs"
else
print "Incorrect Grouping Pairs"
end if
![6) Let's pop one more time
poppeditem = "]"
Design Strategy
We have 3 types of tokens we're looking for:
1) Parenthesis ( )
2) Brackets []
3) Curly Brackets {}
There's an open and closed version of each token.
Look at this line: x = [a, b(1,2,3], c] This is an unmatched pair, because the closed bracket after the
number 3, should have been a closed parenthesis, to complete the open parenthesis before the number
1. Here's what the correct version looks like: x = [a, b(1,2,3), c]
A stack is a perfect data structure to keep track of the tokens in the order they were encountered. For
the tokens to be matched, there always has to be a closed token the directly precedes the same version
of an open token. Anytime we come across a closed token we can just pop off the latest item in a stack
to see if it matches.
Algorithm
Let's read a file a line at a time and scan for tokens on each line. As we encounter an open token, push
it into the stack. When we encounter a closed token we pop an item from the stack and see if it
matches the open token. If it doesn't we print a message saying "Unmatched Pair". When we finish
reading the file we check to see if the queue is empty. If it is "Success" or else it's an unmatched pair.
You can use the partial algorithm below and fill in the rest of it if you'd like. Iľ'm not expecting you to
provide details for managing push and pop functions. You can assume that there's a pop and push
function built in that you can utilize.](https://content.bartleby.com/qna-images/question/c43e03e1-b353-4d50-a726-bab1a8232fef/b40ea67a-c4dc-424b-8dc5-1bde55af32cc/02mpv9_processed.png)
Transcribed Image Text:6) Let's pop one more time
poppeditem = "]"
Design Strategy
We have 3 types of tokens we're looking for:
1) Parenthesis ( )
2) Brackets []
3) Curly Brackets {}
There's an open and closed version of each token.
Look at this line: x = [a, b(1,2,3], c] This is an unmatched pair, because the closed bracket after the
number 3, should have been a closed parenthesis, to complete the open parenthesis before the number
1. Here's what the correct version looks like: x = [a, b(1,2,3), c]
A stack is a perfect data structure to keep track of the tokens in the order they were encountered. For
the tokens to be matched, there always has to be a closed token the directly precedes the same version
of an open token. Anytime we come across a closed token we can just pop off the latest item in a stack
to see if it matches.
Algorithm
Let's read a file a line at a time and scan for tokens on each line. As we encounter an open token, push
it into the stack. When we encounter a closed token we pop an item from the stack and see if it
matches the open token. If it doesn't we print a message saying "Unmatched Pair". When we finish
reading the file we check to see if the queue is empty. If it is "Success" or else it's an unmatched pair.
You can use the partial algorithm below and fill in the rest of it if you'd like. Iľ'm not expecting you to
provide details for managing push and pop functions. You can assume that there's a pop and push
function built in that you can utilize.
Transcribed Image Text:Here is a stack data structure called tokenStack. Initially it is empty. Here is a sequence of tokens that
we are going to push into tokenStack ")", "I", "I", ")"
tokenStack (Empty state)
1) Now let's push the first item in the sequence a closed parenthesis ")" into the stack. The latest item
pushed always goes into position 0. A stack is Last In First Out (LIFO)
|0 )
2) Next item in sequence is a closed bracket "J". Push it into tokenStack. The closed parenthesis that
was in position 0 gets pushed down into position 1 and the closed bracket moves into position 0.
tokenStack looks like this:
|1 |)
3) Let's push another closed bracket "J". Everything in tokenStack gets pushed down 1 position and
the closed bracket gets pushed into position 0.
1
4) One more push. This time another closed parenthesis “)". tokenStack looks like this:
2
| 1
3
5) Now let's pop an item from tokenStack. Popping an item removes the latest element that was
pushed (position 0) into a variable (let's call it poppedltem) and reconfigures the stack so that
element is gone. Here's what tokenStack looks like after popping:
|0 1
poppeditem = ")"
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