Lecture Notes on 30 Nov 2012

def canBalance (nums):
  total = sum (nums)
  partial_sum = 0
  for i in range (len(nums)):
    partial_sum += nums[i]
    if (partial_sum == total - partial_sum):
      return True
  return False

def main():
  print (canBalance([1, 1, 1, 2, 1]))
  print (canBalance([2, 1, 1, 2, 1]))
  print (canBalance([10, 10]))

main()
 
#################################################

def fix34 (nums):
  a = nums[:]
  for i in range (len(a)):
    if (a[i] != 3):
      pass
    else:
      for j in range (len(a)):
        if ((a[j] == 4) and (a[j - 1] != 3)):
          a[j], a[i + 1] = a[i + 1], a[j]
          break
  return a

def main():
  print (fix34([1, 3, 1, 4]))
  print (fix34([1, 3, 1, 4, 4, 3, 1]))
  print (fix34([3, 2, 2, 4]))

main()

#########################################################

def linearIn (outer, inner):
  idx_out = 0;
  idx_in = 0;
  while ((idx_out < len(outer)) and (idx_in < len(inner))):
    if (outer[idx_out] > inner[idx_in]):
      return False
    elif (outer[idx_out] < inner[idx_in]):
      idx_out = idx_out + 1
    else:
      idx_out = idx_out + 1
      idx_in = idx_in + 1
  if (idx_in < len(inner)):
    return False
  else:
    return True;

def main():
  print (linearIn([1, 2, 4, 6], [2, 4]))
  print (linearIn([1, 2, 4, 6], [2, 3, 4]))
  print (linearIn([1, 2, 4, 4, 6], [2, 4]))

main()

###################################################################

def isSubList (a, nums):
  size = len(a)
  for i in range (len(nums) - size + 1):
    b = nums[i:i+size]
    if (a == b):
      return True
  return False

def maxMirror (nums):
  max_size = 0
  for i in range (len(nums)):
    for j in range (len(nums), i, -1):
      a = nums[i:j]
      a.reverse()
      if (isSubList(a, nums)):
        if (len(a) > max_size):
          max_size = len(a)
  return max_size

def main():
  print (maxMirror([1, 2, 3, 8, 9, 3, 2, 1]))
  print (maxMirror([1, 2, 1, 4]))
  print (maxMirror([7, 1, 2, 9, 7, 2, 1]))

main()

##########################################################

def maxSpan (nums):
  span = 0
  limit_i = len(nums)
  limit_j =  limit_i - 1
  for i in range (limit_i):
    for j in range (limit_j, -1, -1):
      if (nums[i] == nums[j]) and ((j - i + 1) > span):
        span = j - i + 1
        break
  return span
    
def main():
  print (maxSpan([1, 2, 1, 1, 3]))
  print (maxSpan([1, 4, 2, 1, 4, 1, 4]))
  print (maxSpan([1, 4, 2, 1, 4, 4, 4]))

main()

###############################################################

def seriesUp (n):
  a = []
  for i in range (1, n + 1):
    for j in range (1, i + 1):
      a.append (j)
  return a

def main ():
  print (seriesUp(3))
  print (seriesUp(4))
  print (seriesUp(2))

main()