Print Statistics
by Isai Damier

#=======================================================================
# Author: Isai Damier
# Title: Singly Linked List
# Project: geekviewpoint
# Package: datastructure
#
# Description: A LinkedList is a data structure that allows access
#   to a collection of data using pointers/references. While an
#   array can also be defined as above, LinkedLists and arrays differ
#   in how they are stored in memory and in the operations they
#   allow. Unlike an array that must be stored in a block of memory,
#   the nodes of a LinkedList can be stored anywhere because each
#   node has a reference to the node that succeeds it. Because the
#   nodes are stored so loosely, inserting nodes into a LinkedList
#   is easy; whereas in an array, all the succeeding elements must
#   be shifted. Of course, insertion also means changing the size of
#   the array, which means creating the entire array anew.
#
#   Perhaps the greatest beauty of LinkedList is that it allows
#   accessing an entire sequence of nodes using only one variable:
#   a reference to the first node in the sequence.
#
#   Countless operations can be performed on LinkedLists. Following
#   are a few, ranging from the common to the very interesting.
#=======================================================================
  #=====================================================================
  # Time Complexity of Solution:
  #   O(n).
  #
  # Description: Retrieve the following statistics about this
  #   LinkedList: min_value, max_value, total, size, and avg.
  #
  # Technical Details:
  #
  #=====================================================================
 
 import collections
class SinglyLinkedList( object ):

  def __init__( self ):
    self.head , self.tail = None, None

  def printStats( self ) : # min_value, max_value, avg, total, size
    if None == self.head:
      return None

    min_value, max_value, total, size = 0, 0, 0, 0
    t = self.head
    while None != t:
      if t == self.head:
        min_value = max_value = self.head.data
      else:
        if min_value > t.data:
          min_value = t.data

        if max_value < t.data:
          max_value = t.data

      total += t.data
      size += 1
      t = t.next
    return [min_value, max_value, total, size, total / size]

class Node( object ):

  def __init__( self, data, next = None ):
    self.data = data
    self.next = next

import unittest
from algorithms.SinglyLinkedList import SinglyLinkedList
import random

class Test( unittest.TestCase ):
  #=====================================================================
  # Test of printStats method, of class SinglyLinkedList.
  #=====================================================================
  def testPrintStats( self ):
    tape = [9, 4, 5, 2, 1, 12, 6, 7, 4, 8, 3, 0, 16, 19, 11]
    linkedList = SinglyLinkedList()
    for i in range( len( tape ) ):
      linkedList.addToTail( tape[i] )

    result = linkedList.printStats()
    expected = [0, 19, 107, 15, 7]
    self.assertEquals( expected, result )