Stack

Question

You need to make a back button for a browser.
You use a stack to store the website links visited. Each new link visited is pushed onto the stack.
The back button needs to pop the top link from the stack and navigate to it.

The given code declares a Browser class as a stack and implements some of its methods. Then, some links are pushed onto the stack.
A while loop is then used to go back to all links and print them.

Implement the required pop() method for the Browser, so that the given code works as expected.
Note, that the pop() method needs to return the value, so that it can be printed.

class Browser:
def __init__(self):
self.links = []

def is_empty(self):
return self.links == []

def push(self, link):
self.links.insert(0, link)

x = Browser()
x.push('about:blank')
x.push('www.sololearn.com')
x.push('www.sololearn.com/courses/')
x.push('www.sololearn.com/courses/JUMP_LINK__&&__python__&&__JUMP_LINK/')

while not x.is_empty():
print(x.pop())

not able to solve problem as unable to understand stack class in python.

Answer 1

class Browser:
def __init__(self):
self.links = []

def is_empty(self):
return self.links == []

def push(self, link):
self.links.insert(0, link)
def pop(self):
return self.links.pop(0)

x = Browser()
x.push('about:blank')
x.push('www.sololearn.com')
x.push('www.sololearn.com/courses/')
x.push('www.sololearn.com/courses/JUMP_LINK__&&__python__&&__JUMP_LINK/')

while not x.is_empty():
print(x.pop())

Answer 2

class Browser:
def __init__(self):
self.links = []

def is_empty(self):
return self.links == []

def push(self, link):
self.links.insert(0, link)

def pop(self):
return self.links.pop(0)

x = Browser()
x.push('about:blank')
x.push('www.sololearn.com')
x.push('www.sololearn.com/courses/')
x.push('www.sololearn.com/courses/JUMP_LINK__&&__python__&&__JUMP_LINK/')

while not x.is_empty():
print(x.links.pop(0))

It works my friends. Please check it.

Answer 3

In browser class

def pop(self):
return self.links.pop(0)

Answer 4

Lothar I agree with you.
But here and there it might be a good idea to provide the code. In this case I think he stood on the pipe.
So he will sich vor den Kopf schlagen and say..
Oh....so easy was it?

10 minutes studying a good solution might be as good as trying 1 hour without result.

But...it depends from case to case.

Answer 5

pop method will remove the last element in stack . So you can implement a pop method with the following functionality ,

return self.links.pop()

Here pop() is a list method in python that removes the last element (which is what pop should do).

Answer 6

print(x.pop(0))

Answer 7

Dharmendra Singh ,

the community will not provide complete solutions. This does not complying with the mission of sololearn. and it does not help you developing your coding knowledge and your problem solving ability.
it is not a problem when someone can not solve a coding task instantly, as you can repeat some parts of the tutorial and then try it again.

happy coding and good success!

Answer 8

oh.. ,is that true, i need to go for python intermediate first & then python data structure, may be that's why im feeling difficulty in solving problems,i have completed python for beginners.

Answer 9

can u please provide complete solution

Answer 10

print(x.links.pop(0))

Answer 11

I think this program is a solution for the problem:
if (evenNums.Peek() % 2 != 0)
{
Console.WriteLine(num + ": Removed");
evenNums.Pop();
}
foreach (var evenNum in evenNums)
{
Console.Write(evenNum + " ");
}