Lecture Notes on 29 Jul 2013

def sum_divisors (n):
  sum = 0
  limit = n // 2 + 1
  for i in range (1, limit):
    if (n % i == 0):
      sum += i

  return sum

def all_count (s, sub):
  count = 0
  index = s.find(sub, 0)
  while (index > -1):
    count += 1
    index = s.find (sub, index + 1)
  return count

def word_freq (inFile, word):
  input = open (inFile, 'r')
  contents = input.read()
  input.close()
  count = contents.count (word)
  return count

def grep (inFile, word):
  line_no = 0
  input = open (inFile, 'r')
  for line in input:
    line_no += 1
    if (line.find(word) > -1):
      print (line_no)
  input.close()

def is_palindromic (s):
  return (s == s.reverse())

def is_anagram (s1, s2):
  a = list (s1)
  b = list (s2)
  a.sort()
  b.sort()
  return (a == b)

def rotate (s, n):
  length = len(s)
  n = n % length
  return s[- n:] + s[: - n]

def scalar_product (a, b):
  sum = 0
  for i in range (len(a)):
    sum = sum + a[i] * b[i]
  return sum

def sequential_search (a, x):
  for i in range (len(a)):
    if (a[i] == x):
      return i
  return -1

def binary_search (a, x):
  lo = 0
  hi = len(a) - 1
  while (lo <= hi):
    mid = (lo + hi) // 2
    if (a[mid] < x):
      lo = mid + 1
    elif (a[mid] > x):
      hi = mid - 1
    else:
      return mid
  return -1