greplin_solutions.py

def part1():
  s = 'FourscoreandsevenyearsagoourfaathersbroughtforthonthiscontainentanewnationconceivedinzLibertyanddedicatedtothepropositionthatallmenarecreatedequalNowweareengagedinagreahtcivilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth'
  substrs = (s[start:l+start] 
              for l in range(1, len(s)) 
              for start in range(0, len(s)-l)
              )
  substrs = ((len(ss), ss) for ss in substrs if s.find(ss[::-1]) != -1)
  return max(substrs, key=lambda x: x[0])

# part 2
def is_prime(n):
  for x in range(2, int(n**0.5)+1):
    if n%x == 0:
      return False
  return True
  
def fib_gen():
  x = y = 1
  while True:
    z = x + y
    yield z
    
    x, y = y, z
    
def get_prime_fib_gt(n):
  fibs = fib_gen()
  while True:
    fib = fibs.next()
    if fib < n:
      continue
    if is_prime(fib):
      return fib
  
def part2():
  X = get_prime_fib_gt(227000)
  prime_divisors = (n for n in range(2, X+1) 
                if (X+1)%n == 0
                and is_prime(n))
  return sum(prime_divisors)
  
# part 3
def part3():
  from itertools import combinations
  nums = [3, 4, 9, 14, 15, 19, 28, 37, 47, 50, 54, 56, 59, 61, 70, 73, 78, 81, 92, 95, 97, 99]
  combs = (combinations(nums, l)
              for l in range(2, len(nums))
              )
  return len([c for cs in combs 
              for c in cs 
              if sum(c[:-1]) == c[-1]])