Sorted. Added 023-026 in Python.

001.hs

@@ -6,42 +6,46 @@ import qualified Data.Set as S
 problem_1 :: Int
 problem_1 = sum . nub $ [3,6..999] ++ [5,10..999]
 problem_1' = sum $ union [3,6..999] [5,10..999]
+main = problem_1'
 
+-- bcs.h
+import Prelude hiding ((>>=), return)
 
--- 2 - all even primes lower 4 million
-problem_2 :: Int
-problem_2 = sum [x | x <- (takeWhile (<= 4000000) ((fix (\f x y -> x:f y (x+y))) 1 1)), even x]
+type Choice a = [a]
 
+choose :: [a] -> Choice a
+choose xs = xs
 
--- 3 - largest prime factor
--- problem_3 :: Integer -> Integer
-prims = fix (\f (x:xs) -> x:f (filter (\y -> rem y x /= 0) xs)) [2..]
-get_prims :: Integer -> [Integer]
-get_prims 1 = []
-get_prims n = let p = head $ dropWhile (\x -> rem n x /= 0) prims
-              in p:get_prims (div n p)
---next_prim xs = head $ dropWhile (\y -> any (\e -> rem y e == 0) xs) [last xs + 1..]
---prims = filter (\x -> not $ any (\n -> rem x n == 0) [2..(x-1)]) [1..] 
---pfactors n = [x | x <- takeWhile (\y ->  y*y <= n) [2..], n `mod` x == 0, null $ pfactors x] 
-problem_3 :: Integer -> Integer
-problem_3 x = last $ get_prims x
+pair456 :: Int -> Choice (Int, Int)
+pair456 x = choose [(x, 4), (x, 5), (x, 6)]
 
+join :: Choice (Choice a) -> Choice a
+join = concat
 
--- 10 - sum prime smaller 2 million
-eres :: Integral a => [a] -> [a]
-eres (x:xs) = if x*x < last xs then x:eres (filter (\y -> rem y x /= 0) xs) else (x:xs)
-problem_10 = sum $ eres [2..2000000]
+-- join $ map pair456 [1,2,3] 
+-- [1, 2, 3] >>= pair456
+(>>=) :: Choice a -> (a -> Choice b) -> Choice b
+choices >>= f = join (map f choices)
 
+return :: a -> Choice a
+return x = [x]
 
--- 11 - biggest multiple in 2d field
-parseSquare :: String -> [[Integer]]
-parseSquare = map (\line -> map read $ words line) . lines
+makePairs :: Choice (Int, Int)
+makePairs = 
+  choose [1, 2, 3] >>= (\x ->
+  choose [4, 5, 6] >>= (\y ->
+  return (x, y)))
 
-columns :: [[a]] -> [[a]]
-columns [[]] = []
-columns xs = map 
+mzero :: Choice a
+mzero = choose []
 
-exercise_11 :: IO ()
-exercise_11 = do
-  fileString <- readFile "problem_11.txt"
-  putStrLn . show $ parseSquare fileString
+guard :: Bool -> Choice ()
+guard True  = return ()
+guard False = mzero
+
+makePairs' :: Choice (Int,Int)
+makePairs' = do
+  x <- choose [1,2,3]
+  y <- choose [4,5,6]
+  guard (x*y == 8)
+  return (x,y)

002.hs

@@ -0,0 +1,3 @@
+-- 2 - all even primes lower 4 million
+problem_2 :: Int
+problem_2 = sum [x | x <- (takeWhile (<= 4000000) ((fix (\f x y -> x:f y (x+y))) 1 1)), even x]

003.hs

@@ -0,0 +1,12 @@
+-- 3 - largest prime factor
+-- problem_3 :: Integer -> Integer
+prims = fix (\f (x:xs) -> x:f (filter (\y -> rem y x /= 0) xs)) [2..]
+get_prims :: Integer -> [Integer]
+get_prims 1 = []
+get_prims n = let p = head $ dropWhile (\x -> rem n x /= 0) prims
+              in p:get_prims (div n p)
+--next_prim xs = head $ dropWhile (\y -> any (\e -> rem y e == 0) xs) [last xs + 1..]
+--prims = filter (\x -> not $ any (\n -> rem x n == 0) [2..(x-1)]) [1..] 
+--pfactors n = [x | x <- takeWhile (\y ->  y*y <= n) [2..], n `mod` x == 0, null $ pfactors x] 
+problem_3 :: Integer -> Integer
+problem_3 x = last $ get_prims x

010.hs

@@ -0,0 +1,4 @@
+-- 10 - sum prime smaller 2 million
+eres :: Integral a => [a] -> [a]
+eres (x:xs) = if x*x < last xs then x:eres (filter (\y -> rem y x /= 0) xs) else (x:xs)
+problem_10 = sum $ eres [2..2000000]

011.hs

@@ -0,0 +1,12 @@
+-- 11 - biggest multiple in 2d field
+parseSquare :: String -> [[Integer]]
+parseSquare = map (\line -> map read $ words line) . lines
+
+columns :: [[a]] -> [[a]]
+columns [[]] = []
+columns xs = map 
+
+main :: IO ()
+main = do
+  fileString <- readFile "problem_11.txt"
+  putStrLn . show $ parseSquare fileString

023.py

@@ -0,0 +1,40 @@
+import math
+
+
+def get_proper_divisors(n):
+    proper_divisors = set([1])
+    for i in range(2, int(math.sqrt(n)) + 1):
+        if n % i == 0:
+            proper_divisors.add(i)
+            proper_divisors.add(n / i)
+    return proper_divisors
+
+
+def is_abundant(n):
+    return sum(get_proper_divisors(n)) > n
+
+
+def get_abundant_numbers_smaller(n):
+    ret = []
+    for i in range(1, n):
+        if is_abundant(i):
+            ret.append(i)
+    return ret
+
+
+def is_sum_of_two_abundant(n, abundant_numbers):
+    abundant_numbers_set = set(abundant_numbers)
+    for a1 in abundant_numbers:
+        if a1 > n:
+            return False
+        elif (n - a1) in abundant_numbers_set:
+            return True
+            
+    
+if __name__ == "__main__":
+    abundant_numbers = get_abundant_numbers_smaller(30000)
+    cannot_be_written_as_sum_of_abundant = []
+    for i in range(28129):
+        if not is_sum_of_two_abundant(i, abundant_numbers):
+            cannot_be_written_as_sum_of_abundant.append(i)
+    print(sum(cannot_be_written_as_sum_of_abundant))

024.py

@@ -0,0 +1,2 @@
+from itertools import permutations
+print("".join(list(permutations("0123456789"))[1000000-1]))

025.py

@@ -0,0 +1,109 @@
+from copy import deepcopy
+from itertools import islice
+
+
+def primes(n):
+    """ Nice way to calculate primes.  Should be fast. """
+    l = range(2, n + 1)
+    _l = []
+    while True:
+        p = l[0]
+        if p * p > n:
+            return _l + l
+        l = [i for i in l if i % p != 0]
+        _l.append(p)
+
+
+def calculate_decimal_places(numerator, denominator):
+    numerator = (numerator - (numerator / denominator) * denominator) * 10
+    digits = []
+    while True:
+        digit = numerator / denominator
+        numerator = (numerator - digit * denominator) * 10
+        digits.append(digit)
+        if digits[-3:] == [0, 0, 0]:
+            raise StopIteration
+        yield digit
+
+
+def has_cycle(decimal_places, n):
+    d = decimal_places
+    return list(islice(d, 0, n)) == list(islice(d, 0, n)) and \
+           list(islice(d, 0, n)) == list(islice(d, 0, n))
+
+
+def f_025_1():
+    """ Second try.  I realized that only primes must be
+    checked.  Therefore, my brute force approach worked. """
+    l = []
+    for d in primes(1000):
+        for i in range(5, 10000):
+            decimal_places = calculate_decimal_places(1, d)
+            if has_cycle(decimal_places, i):
+                l.append((i, d))
+                break
+    print(max(l))
+
+
+def calculate_cycle(numerator, denominator):
+    numerator = (numerator - (numerator / denominator) * denominator) * 10
+    remainders = set([])
+    while True:
+        digit = numerator / denominator
+        remainder = (numerator - digit * denominator)
+        if remainder in remainders:
+            raise StopIteration
+        remainders.add(remainder)
+        numerator = remainder * 10
+        yield digit
+
+
+def f_025_2():
+    """ Understood trick with remembering remainder... """
+    s = [(len(list(calculate_cycle(1, d))), d)
+         for d in range(1, 1001)]
+    print(max(s))
+
+
+def f_025_3():
+    """ Only testing primes... """
+    s = [(len(list(calculate_cycle(1, d))), d)
+         for d in primes(10000)]
+    print(max(s))
+
+
+f_025_3()
+
+
+#print([(find_cycle_count(calculate_decimal_places(1, d)), d)
+#       for d in range(1, 100)])
+
+#print(find_cycle_count(calculate_decimal_places(22, 7)))
+
+#l = []
+#for d in range(1, 1000):
+#    for i in range(5, 1000):
+#        decimal_places = calculate_decimal_places(1, d)
+#        if has_cycle_one_off(decimal_places, i):
+#            l.append((i, d))
+#            break
+#        decimal_places = calculate_decimal_places(1, d)
+#        if has_cycle(decimal_places, i):
+#            l.append((i, d))
+#            break
+
+#def find_cycle_count(decimal_places):
+#    cycles = []
+#    for digit in decimal_places:
+#        new_cycles = []
+#        for cycle in cycles:
+#            digits, length = cycle
+#            if digits[0] == digit:
+#                if len(digits[1:]) == 0:
+#                    return length
+#                new_cycles.append((digits[1:], length))
+#            new_cycles.append((digits + [digit], length + 1))
+#        new_cycles.append(([digit], 1))
+#        cycles = new_cycles
+
+

026.py

@@ -0,0 +1,38 @@
+def primes(n):
+    """ Nice way to calculate primes.  Should be fast. """
+    l = range(2, n + 1)
+    _l = []
+    while True:
+        p = l[0]
+        if p * p > n:
+            return _l + l
+        l = [i for i in l if i % p != 0]
+        _l.append(p)
+
+
+def produce_prime(a, b, n, primes):
+    x = n*n + a*n + b
+    return x in primes
+    
+
+
+def f_027():
+    """ n^2 + a*n + b
+        1) b must be prime
+    """
+    p6 = set(primes(1000000))
+    p3 = primes(1000)
+    options = [(a, b)
+               for a in range(1, 1000, 2)
+               for b in p3]
+
+    print(len(options))
+    for n in range(100):
+        options = [(a, b)
+                   for a, b in options
+                   if produce_prime(a, b, n, p6)]
+        print(options)
+    print(len(options))
+
+
+f_027()

bcs.hs

@@ -1,40 +0,0 @@
-import Prelude hiding ((>>=), return)
-
-type Choice a = [a]
-
-choose :: [a] -> Choice a
-choose xs = xs
-
-pair456 :: Int -> Choice (Int, Int)
-pair456 x = choose [(x, 4), (x, 5), (x, 6)]
-
-join :: Choice (Choice a) -> Choice a
-join = concat
-
--- join $ map pair456 [1,2,3] 
--- [1, 2, 3] >>= pair456
-(>>=) :: Choice a -> (a -> Choice b) -> Choice b
-choices >>= f = join (map f choices)
-
-return :: a -> Choice a
-return x = [x]
-
-makePairs :: Choice (Int, Int)
-makePairs = 
-  choose [1, 2, 3] >>= (\x ->
-  choose [4, 5, 6] >>= (\y ->
-  return (x, y)))
-
-mzero :: Choice a
-mzero = choose []
-
-guard :: Bool -> Choice ()
-guard True  = return ()
-guard False = mzero
-
-makePairs' :: Choice (Int,Int)
-makePairs' = do
-  x <- choose [1,2,3]
-  y <- choose [4,5,6]
-  guard (x*y == 8)
-  return (x,y)