Hey guys,

This was a weird onsite interview that has been bugging me even after the feedback recieved.

Question
Design a data structure to implement the following set of operations
get(x)
set(x, ..)
begin()
commit()
end()

Example,

begin()
set(x,2)

begin()
set(x,3)
get(x) -> needs to return 3

begin()
set(x,6)
commit()

get(x) -> needs to return 6 because of commit call will pass to the parent scope.
end()

get(x) -> needs to return 2, as end() will conclude the child scope.
end()

Thoughts,

I basically dabbled between a HashMap and then after writing some code. I quickly made it succinct to have it just be a Linkedlist datastructure and an inner class that maintains a HashMap of all the keys and its latest values. with a global committed store.

Example

class Solution {
LinkedList<Level> levels.

.....
class Level {
HashMap<String, Integer> levelKeys

}
}

The above LinkedList data structure. The head will have the latest scope and its keys values. But, if you cannot find the key in the latest scope, then you traverse forward towards tail until you find one.

Was my approach wrong? They said I dabbled between data structures and couldnt complete the final method get. Why did i get digned on completeness if the approach was correct for the given timeframe.