We have an implementation that supports the following operations on a stack (in the instructions below, is the name of the stack).
isempty (s) : returns if is empty, and otherwise.
top (s) : returns the top element of the stack, but does not pop the stack; returns if the stack is empty.
push (s,x) : places on top of the stack.
pop(s) : pops the stack; does nothing if is empty.
Consider the following code:
for i=1 to length(x):
if (x[i] == '('):
while not isempty(s):
What is the output of this program when