Solve 2016 days 4 and 5.

2016/d4.py

@@ -0,0 +1,44 @@
+from lib import *
+
+second = True
+data = open(0).read()
+
+
+def decipher(cipher, shift):
+    clear = ""
+    for c in cipher:
+        if c == "-":
+            nc = "-"
+        else:
+            nc = LETTERS_LOWER[(LETTERS_LOWER.index(c) + shift) % len(LETTERS_LOWER)]
+        clear += nc
+    return clear
+
+
+if not second:
+    s = 0
+    for line in data.splitlines():
+        hash, key = line.split("[")
+        key = key.replace("]", "")
+
+        counts = {}
+        for c in LETTERS_LOWER:
+            counts[c] = hash.count(c)
+
+        counts = sorted(list(zip(counts.values(), counts.keys())), key=lambda t: (t[0], -ord(t[1])), reverse=True)
+
+        real = True
+        for i, (_, c) in enumerate(counts[:5]):
+            if c != key[i]:
+                real = False
+        if real:
+            s += int(hash.split("-")[-1])
+    print(s)
+else:
+    for line in data.splitlines():
+        line = line[:-7]
+        hash = "-".join(line.split("-")[:-1])
+        shift = int(line.split("-")[-1])
+        cleartext = decipher(hash, shift)
+        if "north" in cleartext and "pole" in cleartext:
+            print(shift)