Water - Kareha #14
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Water - Kareha #14
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CheezItMan
reviewed
Apr 15, 2021
lib/problems.rb
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| # Time Complexity: O(n*m) | ||
| # Space Complexity: O(m), but also potentially O(1) | ||
| def balanced(string) |
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👍 Since you're building a stack it can't be O(1)
lib/problems.rb
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| stack = Stack.new | ||
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| string.each_char do |char| # time: O(n) | ||
| if hash_table.has_value?(char) # time: O(m)? |
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I don't think you need to use has_value here.
I think better something like this
matching_braces = {
"}" => "{",
")" => "(",
"]" => "[",
}
stack = Stack.new
string.each_char do |char|
if ! matching_braces[char]
stack.push(char)
elsif matching_braces[char] != stack.pop()
return false
end
end
return stack.empty()
lib/problems.rb
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| # Time Complexity: O(n) | ||
| # Space Complexity: O(m), but also potentially O(1) | ||
| def evaluate_postfix(postfix_expression) |
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👍 , but the space and time complexities are O(n)
| # @store = ... | ||
| raise NotImplementedError, "Not yet implemented" | ||
| @store = Array.new(SIZE) | ||
| @front = @back = -1 | ||
| end | ||
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| def enqueue(element) |
| @back += 1 | ||
| end | ||
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| @store[@back] = element | ||
| end | ||
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| def dequeue |
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| def front | ||
| raise NotImplementedError, "Not yet implemented" | ||
| return @store[@front] | ||
| end | ||
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| def size | ||
| raise NotImplementedError, "Not yet implemented" | ||
| return @store.select{|x| !x.nil?}.length | ||
| end | ||
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| def empty? | ||
| raise NotImplementedError, "Not yet implemented" | ||
| @store.map{|x| x.nil?}.all? | ||
| end |
| end | ||
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| def empty? | ||
| raise NotImplementedError, "Not yet implemented" | ||
| @store.map{|x| x.nil?}.all? | ||
| end | ||
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| def to_s |
| @@ -1,19 +1,18 @@ | |||
| class Stack | |||
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Stacks and Queues
Thanks for doing some brain yoga. You are now submitting this assignment!
Comprehension Questions
push- add element to stack 2.pop- remove top element from stack 3.is_empty?- boolean, return true if stack is empty, else return falseenqueue- add to back of queue 2.dequeue- remove from front of queue 3.is_empty- boolean, return true if queue is empty, else return falseOPTIONAL JobSimulation