Not getting the approach

#1

I know I’ve to use stacks. It is similar to balanced parentheses. But I’m not getting what are the conditions to be used.

#2

follow this approach
push everything into stack except ‘)’ when u encounter ‘)’ store the top of stack and then pop it
now run a while loop till u hit ‘(’ inside the loop, pop the elements of the stack and increase a counter initialised to zero, if the counter at the end of the while loop>0 then it is not duplicate else it is duplicate
this is because if counter is zero then a ‘(’ is encountered before any other element which indicates redundancy

#3


this is the code for it too,
do try before jumping right to it
if your doubt is solved, please mark it as resolved