Added 2018/01

2018/01/1.md

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+## \-\-- Day 1: Chronal Calibration \-\--
+
+\"We\'ve detected some temporal anomalies,\" one of Santa\'s Elves at
+the [Temporal Anomaly Research and Detection Instrument
+Station]{title="It's about as big on the inside as you expected."} tells
+you. She sounded pretty worried when she called you down here. \"At
+500-year intervals into the past, someone has been changing Santa\'s
+history!\"
+
+\"The good news is that the changes won\'t propagate to our time stream
+for another 25 days, and we have a device\" - she attaches something to
+your wrist - \"that will let you fix the changes with no such
+propagation delay. It\'s configured to send you 500 years further into
+the past every few days; that was the best we could do on such short
+notice.\"
+
+\"The bad news is that we are detecting roughly *fifty* anomalies
+throughout time; the device will indicate fixed anomalies with *stars*.
+The other bad news is that we only have one device and you\'re the best
+person for the job! Good lu\--\" She taps a button on the device and you
+suddenly feel like you\'re falling. To save Christmas, you need to get
+all *fifty stars* by December 25th.
+
+Collect stars by solving puzzles. Two puzzles will be made available on
+each day in the Advent calendar; the second puzzle is unlocked when you
+complete the first. Each puzzle grants *one star*. Good luck!
+
+After feeling like you\'ve been falling for a few minutes, you look at
+the device\'s tiny screen. \"Error: Device must be calibrated before
+first use. Frequency drift detected. Cannot maintain destination lock.\"
+Below the message, the device shows a sequence of changes in frequency
+(your puzzle input). A value like `+6` means the current frequency
+increases by `6`; a value like `-3` means the current frequency
+decreases by `3`.
+
+For example, if the device displays frequency changes of
+`+1, -2, +3, +1`, then starting from a frequency of zero, the following
+changes would occur:
+
+-   Current frequency ` 0`, change of `+1`; resulting frequency ` 1`.
+-   Current frequency ` 1`, change of `-2`; resulting frequency `-1`.
+-   Current frequency `-1`, change of `+3`; resulting frequency ` 2`.
+-   Current frequency ` 2`, change of `+1`; resulting frequency ` 3`.
+
+In this example, the resulting frequency is `3`.
+
+Here are other example situations:
+
+-   `+1, +1, +1` results in ` 3`
+-   `+1, +1, -2` results in ` 0`
+-   `-1, -2, -3` results in `-6`
+
+Starting with a frequency of zero, *what is the resulting frequency*
+after all of the changes in frequency have been applied?
+
+Your puzzle answer was `474`.
+
+## \-\-- Part Two \-\-- {#part2}
+
+You notice that the device repeats the same frequency change list over
+and over. To calibrate the device, you need to find the first frequency
+it reaches *twice*.
+
+For example, using the same list of changes above, the device would loop
+as follows:
+
+-   Current frequency ` 0`, change of `+1`; resulting frequency ` 1`.
+-   Current frequency ` 1`, change of `-2`; resulting frequency `-1`.
+-   Current frequency `-1`, change of `+3`; resulting frequency ` 2`.
+-   Current frequency ` 2`, change of `+1`; resulting frequency ` 3`.
+-   (At this point, the device continues from the start of the list.)
+-   Current frequency ` 3`, change of `+1`; resulting frequency ` 4`.
+-   Current frequency ` 4`, change of `-2`; resulting frequency ` 2`,
+    which has already been seen.
+
+In this example, the first frequency reached twice is `2`. Note that
+your device might need to repeat its list of frequency changes many
+times before a duplicate frequency is found, and that duplicates might
+be found while in the middle of processing the list.
+
+Here are other examples:
+
+-   `+1, -1` first reaches `0` twice.
+-   `+3, +3, +4, -2, -4` first reaches `10` twice.
+-   `-6, +3, +8, +5, -6` first reaches `5` twice.
+-   `+7, +7, -2, -7, -4` first reaches `14` twice.
+
+*What is the first frequency your device reaches twice?*
+
+Your puzzle answer was `137041`.
+
+Both parts of this puzzle are complete! They provide two gold stars:
+\*\*
+
+At this point, you should [return to your Advent calendar](/2018) and
+try another puzzle.
+
+If you still want to see it, you can [get your puzzle
+input](1/input).
+

2018/01/solution.py

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+#!/bin/python3
+import sys,re
+from pprint import pprint
+sys.path.insert(0, '../../')
+from fred import list2int
+
+input_f = 'input'
+
+part = 2
+#########################################
+#                                       #
+#              Part 1                   #
+#                                       #
+#########################################
+
+if part == 1:
+    count = 0
+    with open(input_f) as file:
+        for line in file:
+            count += int(line.rstrip())
+    print(count)
+
+
+#########################################
+#                                       #
+#              Part 2                   #
+#                                       #
+#########################################
+if part == 2:
+    count = 0
+    instructions = []
+    with open(input_f) as file:
+        for line in file:
+            instructions.append(int(line.rstrip()))
+    
+    index = 0
+    duplicates = []
+    while True:
+        count += instructions[index]
+        index += 1
+        if count in duplicates:
+            print(count)
+            break
+        duplicates.append(count)
+        if index == len(instructions):
+            index = 0
+