Add solution for problem-59 and a C solution for problem 40

problem-59.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+
+import itertools
+import requests
+import string
+
+URL = "https://projecteuler.net/project/resources/p059_cipher.txt"
+
+def get_ciphertext(url):
+    resp = requests.get(url)
+    return resp.text
+
+
+def generate_keys(letters, length):
+    perms = itertools.permutations(letters, length)
+    yield from perms
+
+
+def ints_to_string(numbers):
+    return [chr(num) for num in numbers]
+
+
+def string_to_ints(letters):
+    return [ord(letter) for letter in letters]
+
+
+def xor_lists(xs, ys):
+    if len(xs) != len(ys):
+        raise Exception("Lists must be the same length")
+
+    return [a ^ b for a, b in zip(xs, ys)]
+
+
+def main():
+    text = get_ciphertext(URL)
+    cipher = [int(num) for num in text.split(',')]
+    letters = string.ascii_lowercase
+    common_words = ["the", "of", "to", "and", "in", "is", "it", "that"]
+    for perm in generate_keys(letters, 3):
+        key = "".join(list(perm))
+        cycled = string_to_ints(list(key * (len(cipher) // len(key))))
+        decrypt = "".join(ints_to_string(xor_lists(cipher, cycled)))
+        if all(word in decrypt for word in common_words):
+            print("Decrypted passage:")
+            print(decrypt)
+            print("Key: {0}".format(key))
+            print("Sum: {0}".format(sum(xor_lists(cipher, cycled))))
+
+
+if __name__ == "__main__":
+    main()