Question

Part III: Matching Brackets (20 points) Write a function brackets (expr) that takes a string consisting only of the symbols (,), [, ], and { }, and analyzes the string to make sure that the brackets are all "balanced" (matched) properly. For example the strings "((()))" and "(())(()))" contain balanced brackets, whereas "((])", "(()))", and "([)]" are unbalanced. We refer to (, [, and { as "left brackets", and ), ], and } as "right brackets". The basic algorithm to implement works like this: input: a string S output: a list L for each character in S CSE 101 -- Spring 2018 Homework #3 Page 3 if the character is a left bracket append the character to L else if the character is a right bracket, but L is empty return the string "error" else if the character is a right bracket and the rightmost element of L is a matching left bracket delete the rightmost element of L (because we have a match) else we must have a mismatch, so return L Note that if the original string is properly balanced, the return value should be an empty list. Hint: You can use the pop method to remove an item from a list. Take a look at the documentation at https://docs.python.org/3.6/tutorial/datastructures.html. Examples: Function Call brackets(((((()))))) brackets(()) brackets([]) brackets({}) brackets(() brackets([)] brackets({}) brackets(((()) brackets((())) brackets([]) brackets({}) brackets([{}]) brackets({[]}) brackets([]) brackets({}) brackets((((())))) brackets((())) brackets([]) brackets({})

          Part III: Matching Brackets (20 points)
Write a function brackets (expr) that takes a string consisting only of the symbols (,), [, ], and { }, and
analyzes the string to make sure that the brackets are all "balanced" (matched) properly. For example the strings
"((()))" and "(())(()))" contain balanced brackets, whereas "((])", "(()))", and "([)]" are unbalanced.
We refer to (, [, and { as "left brackets", and ), ], and } as "right brackets".
The basic algorithm to implement works like this:
input: a string S
output: a list L
for each character in S
CSE 101 -- Spring 2018
Homework #3
Page 3
if the character is a left bracket
append the character to L
else if the character is a right bracket, but L is empty
return the string "error"
else if the character is a right bracket and
the rightmost element of L is a matching left bracket
delete the rightmost element of L (because we have a match)
else we must have a mismatch, so return L
Note that if the original string is properly balanced, the return value should be an empty list.
Hint: You can use the pop method to remove an item from a list. Take a look at the documentation at
https://docs.python.org/3.6/tutorial/datastructures.html.
Examples:
Function Call
brackets(((((())))))
brackets(())
brackets([])
brackets({}) 
brackets(()
brackets([)]
brackets({})
brackets(((())
brackets((()))
brackets([])
brackets({}) 
brackets([{}])
brackets({[]})
brackets([])
brackets({}) 
brackets((((()))))
brackets((()))
brackets([])
brackets({})

Part III: Matching Brackets (20 points)
Write a function brackets (expr) that takes a string consisting only of the symbols (,), [, ], and , and
analyzes the string to make sure that the brackets are all "balanced" (matched) properly. For example the strings
"((()))" and "(())(()))" contain balanced brackets, whereas "((])", "(()))", and "([)]" are unbalanced.
We refer to (, [, and as "left brackets", and ), ], and as "right brackets".
The basic algorithm to implement works like this:
input: a string S
output: a list L
for each character in S
CSE 101 – Spring 2018
Homework #3
Page 3
if the character is a left bracket
append the character to L
else if the character is a right bracket, but L is empty
return the string "error"
else if the character is a right bracket and
the rightmost element of L is a matching left bracket
delete the rightmost element of L (because we have a match)
else we must have a mismatch, so return L
Note that if the original string is properly balanced, the return value should be an empty list.
Hint: You can use the pop method to remove an item from a list. Take a look at the documentation at
https://docs.python.org/3.6/tutorial/datastructures.html.
Examples:
Function Call
brackets(((((())))))
brackets(())
brackets([])
brackets()
brackets(()
brackets([)]
brackets()
brackets(((())
brackets((()))
brackets([])
brackets()
brackets([])
brackets([])
brackets([])
brackets()
brackets((((()))))
brackets((()))
brackets([])
brackets()

Added by Darlene I.

Question

Please give Ace some feedback