python - Incorrectly returning the value of a Node at position 'm' in a linked list -

i have homework problem:

find element in singly linked list that's m elements end. example, if linked list has 5 elements, 3rd element end 3rd element. function definition should question5(ll, m), ll first node of linked list , m "mth number end". should copy/paste node class below use representation of node in linked list. return value of node @ position.

the code paste 4-line definition of class node. attempt follows.

class node(object):   def __init__(self, data):     self.data = data     self.next = none  ll = none  # provided node class. class node(object):     def __init__(self, data):         self.data = data         self.next = none  # function adding values list. def add(new_data):     global ll     node = node(new_data)     node.next = ll     ll = node  def question5(ll, m):     # start of list.     element = ll     # node count.     c = 0     # set end of list false.     endlist = false     # loop until linked list reaches end.     while not endlist:         c += 1         element = element.next         if element.next == none:             endlist = true      # set node value count - position m     position = c - m     # if position less 0, end has been reached     if(m < 0):         return "8, end of list"     # if not end of list return value @ position m     else:         return position  global ll add(1) add(2) add(3) add(4) add(5) add(6) add(7) add(8) print ("value of node @ position m end is: ", question5(ll, -1)) #('value of node @ position m end is: ', '8, end of list') print ("value of node @ position m end is: ", question5(ll, 3)) #('value of node @ position m end is: ', 4) print ("value of node @ position m end is: ", question5(ll, 2)) #('value of node @ position m end is: ', 5) print ("value of node @ position m end is: ", question5(ll, 0)) #('value of node @ position m end is: ', 7) 

my reviewer says solution incorrect, not returning actual value of node @ position 'm'. correct way return value of node object in scenario?

---

edit: sake of finalizing question have included solution able implement per advice in second answer below

new code:

ll = none  # provided node class. class node(object):     def __init__(self, data):         self.data = data         self.next = none  # function adding values list. def add(new_data):     global ll     node = node(new_data)     node.next = ll     ll = node  def question5(ll, m):     # nodes traversed     element1 = ll     # nodes beginning     element2 = ll     # node count.     c = 0      # traverse list until c = m     if(ll not none):         while(c < m):             element2 = element2.next             c += 1      # loop until linked list reaches end.     while(element2 not none):         #print ("this element 1:", element1.data)         #print ("this element 2:", element2.data)         element1 = element1.next         element2 = element2.next      # return current node @ m steps end     return element1.data  global ll # list meant represent telephone 0 being end. add("0") add("9 wxyz") add("8 tuv") add("7 pqrs") add("6 mno") add("5 jkl") add("4 ghi") add("3 def") add("2 abc") add("1") # singly linked list: # 1 - 2 abc - 3 def - 4 ghi - 5 jkl - 6 mno - 7 pqrs - 8 tuv - 9 wxyz - 0 print ("node @ position m in relation end of ll is: ", question5(ll, 4)) # ('node @ position m in relation end of ll is: ', '7 pqrs') print ("node @ position m in relation end of ll is: ", question5(ll, 8)) # ('node @ position m in relation end of ll is: ', '3 def') print ("node @ position m in relation end of ll is: ", question5(ll, 1)) # ('node @ position m in relation end of ll is: ', '0') print """---end question 5--- 

look @ output: when m 2, code returns 5. problem statement shows expects 7, second element counting form end of list. code backs off 2 elements: apparently, way allow returning 8 give position of -1, , 0 required value of 7.

fix counting, , you'll fine; you're handling traversal correctly.

---

now i've had time on code, i'm going off previous answer somewhat: end of list properly, that's code correctly. @ functional standpoint, reviewer entirely correct: don't return node's value @ all. compute position , assume node's value matches. you're not allowed that.

consider list built way, on phone buttons:

add("abc") add("def") add("ghi") add("jkl") add("mno") add("prs") add("tuv") add("wxy") add("qz") 

if input 2, have return "wxy". tried question5 code, , still returns numbers. wrong.

you have find way end of list, , find proper value end of list. there various ways this. instance, build list of node values traverse list; print value position -m in list. possibility use recursion find end of list, return counter recursion chain figure out instance should print value of current node.

can take next steps on own.