Day 11 solutions.

day-11/input.txt

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+hxbxwxba

day-11/solution.py

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+import string
+
+letters = [c for c in string.lowercase]
+
+password = "hxbxwxba"
+
+forbidden = set([letters.index(c) for c in "iol"])
+passwordCode = [letters.index(c) for c in password]
+
+def convert(password):
+    return [letters.index(c) for c in password]
+
+def isOk(password):
+    hasStreak = False
+    prev = -2
+    streak = 1
+    same = 0
+    sameChar = None
+    for x in password:
+        if x in forbidden:
+            return False
+
+        if x == prev + 1:
+            streak += 1
+            if streak >= 3:
+                hasStreak = True
+        else:
+            streak = 1
+
+        if x == prev and x is not sameChar:
+            same += 1
+            sameChar = x
+
+        prev = x
+
+    return hasStreak and same >= 2
+
+def incrementForbidden(password):
+    for idx, x in enumerate(password):
+        if x in forbidden:
+            password[idx] = (x + 1) % len(letters)
+            for i in range(idx + 1, len(password)):
+                password[i] = 0
+
+            return
+
+def increment(password):
+    carry = True
+    i = len(password)
+    while carry and i > 0:
+        i -= 1
+        password[i] = (password[i] + 1) % len(letters)
+        carry = password[i] == 0
+
+    incrementForbidden(password)
+
+for x in range(2):
+    increment(passwordCode)
+    while not isOk(passwordCode):
+        increment(passwordCode)
+    
+    print "Next password is", ''.join([letters[c] for c in passwordCode])