Data structure

Question 1

is empty

Answer 1

def isempty(stk):
if stk==[]:
return true
else:
return false

Question 2

push

Answer 2

def push(stk,item):
stk.append(item)
top=len(stk)-1

Question 3

pop

Answer 3

def pop(stk):
is isempty(stk):
return “underflow”
else:
item=stk.pop()
if len(stk)==0:
top=None
else:
top=len(stk)-1
return item

Question 4

peek

Answer 4

def peek(stk):
if isempty(stk):
return “underflow”
else:
top=len(stk)-1
return stk[top]