Beat 99.95% of submitted solutions for Merge Two Sorted Linked Lists

Yes, I did it again. Simple enough.

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        head=None
        cur=None
        while l1 is not None or l2 is not None:
            if head is None:
                if  l1 is not None and l2 is not None and l1.val<l2.val:
                    head=l1
                    l1=l1.next
                    cur=head
                elif l1 is not None and l2 is not None and l1.val>l2.val:
                    head=l2
                    l2=l2.next
                    cur=head
                elif l1 is None and l2 is not None:
                    head=l2
                    l2=l2.next
                    cur=head
                else:
                    head=l1
                    l1=l1.next
                    cur=head
            elif l1 is not None and l2 is not None and l1.val<l2.val:
                cur.next=l1
                l1=l1.next
                cur=cur.next
            elif  l1 is not None and l2 is not None and l1.val>l2.val:
                cur.next=l2
                l2=l2.next
                cur=cur.next
            elif  l1 is None and l2 is not None:
                cur.next=l2
                l2=l2.next
                cur=cur.next
            else:
                cur.next=l1
                l1=l1.next
                cur=cur.next
        return head

                
                
                

Beat 95.56% of python submissions

Good result. I'm happy.

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def removeNthFromEnd(self, head, n):
        """
        :type head: ListNode
        :type n: int
        :rtype: ListNode
        """
        count=0
        tmp=list()
        cur=head
        while cur is not None:
            # if count>n:
            #     break
            tmp.append(cur)
            cur=cur.next
            count+=1

        if count==1 and n==1:
            return None
        
        if n==1:
            tmp[len(tmp)-n-1].next=None
            return head
        
        if n==len(tmp):
            head=None
            head=tmp[1]
            return head
        
        if n>0:
            tmp[len(tmp)-n-1].next=tmp[len(tmp)-n+1]
            return head

    

if __name__ =='__main__':
    s=Solution()
    class ListNode:
        def __init__(self, x):
            self.val = x
            self.next = None
            self.head=self
        
        def add_to_the_end(self, val):
            cur=self.head
            while cur.next is not None:
                cur=cur.next
            cur.next=ListNode(val)
           
            
            
        
        def printLinkedList(self):
            cur =self.head
            while cur is not None:
                print (cur.val)
                cur=cur.next 
            
    ln=ListNode(1)
    ln.add_to_the_end(2)
    ln.add_to_the_end(3)
    ln.add_to_the_end(4)
    ln.add_to_the_end(5)
    s.removeNthFromEnd(ln,5)
    ln.printLinkedList()

        

Beat 100% of python3 submissions

Yes! I did it.

Here is simple code that  gives me  performance  described on picture above.

class powxy:
    def pow(self, x, n):
        if n == 0.0:
            return 1
        if n < 0:
            n = -n
            x = 1/x
        if n % 2 == 0:
            return self.pow(x*x, int(n/2))
        return x*self.pow(x*x, int(n/2))

How to use virtual invironment in python 3.6

A Virtual Environment, allows to create an isolated working copy of Python. It is quite common situation  when Python applications  use packages  that  are not part of the standard library. It happens that  multiple applications may require different version of the same library. In other words- single installation of  Python  will not be able to serve  all the possible requirements  for   applications. This issue  can be solved by utilizing  Virtual environments. Virtual environment is directory that contains  all the Python installation  and all the required  packages.  Different Python application may use  dedicated  virtual environments.

Starting Python 3.6  -  virtual environment  creation module shipped  as part of Python installation.

Here is example - how to create virtual environment using Python 3.6

python -m venv env

This command creates new forlder "env" in current directory (if directory not yet exists). It also create subdirectories in "env" directory that   containing a copy of the Python interpreter, the standard library,  supporting files, etc.

After  virtual environment is created- it needs to be activated:
Depend on  OS type- it can be done in several ways.

For Windows:

.\env\Scripts\activate.bat

For Linux:

./env/Scripts/activate.sh

After  virtual environment is activated-  shell will show  activated virtual  environment as a prefix in command prompt: (venv).

Now we can install  all the required libraries for our current  Python application.
For example:

python -m pip install beautifulsoup4

python -m pip install lxml

All the installed packages  will be stored inside of "venv" folder  and not overlap/affect any other Python  applications.
v