Day 4

2019/04a.py

@@ -0,0 +1,26 @@
+# Python 3.7
+
+def main():
+    rangeStart = 109165
+    rangeEnd = 576723
+    count = 0
+    for pw in range(rangeStart, rangeEnd):
+        count += validatePassword(pw)
+    print(count)
+
+def validatePassword(pw):
+    pwStr = str(pw)
+    # does it have a doubled digit
+    # does it have a descending digit
+    c, d = 0, 0
+    for i in range(1, len(pwStr)):
+        if pwStr[i-1] == pwStr[i]:
+            c = 1
+        if int(pwStr[i]) < int(pwStr[i-1]):
+            d = 1
+    if c == 0 or d == 1:
+        return 0
+    return 1
+
+if __name__ == "__main__":
+    main()

2019/04b.py

@@ -0,0 +1,33 @@
+# Python 3.7
+
+def main():
+    rangeStart = 109165
+    rangeEnd = 576723
+    count = 0
+    for pw in range(rangeStart, rangeEnd):
+        count += validatePassword(pw)
+    print(count)
+
+def validatePassword(pw):
+    pwStr = str(pw)
+    # does it have a doubled digit
+    #  but not a tripled etc. digit!
+    # does it have a descending digit
+    c, d, m = 0, 0, ""
+    for i in range(1, len(pwStr)):
+        if pwStr[i-1] == pwStr[i]:
+            if c == 0 and m == "": # it has a doubled digit we haven't seen before
+                c = 1
+                m = pwStr[i]
+            elif c == 1 and m == pwStr[i]: # it has a doubled digit we HAVE seen before
+                c = 0                      # so it doesn't count :(
+        else: # this digit isn't the same as the previous, so reset the memo
+            m = ""
+        if int(pwStr[i]) < int(pwStr[i-1]):
+            d = 1
+    if c == 0 or d == 1:
+        return 0
+    return 1
+
+if __name__ == "__main__":
+    main()