#=======================================================================
# 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 )
