Xah Talk Show 2022-12-21 Advent of Code Day 6, in WolframLang, Live Coding

part 1

Given a string, find the first 4 sequence of characters that are all different. what is the last index of the character. (count start at 1)

examples:

• b vwbj plbgvbhsrlpgdmjqwftvncz → 5
• np pdvj thqldpwncqszvftbrmjlhg → 6
• nznrnf rfnt jfmvfwmzdfjlvtqnbhcprsg → 10
• zcfzfwz zqfr ljwzlrfnpqdbhtmscgvjw→ 11

x1 = "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw"

Position[ Map[ Function[{x}, UnsameQ @@  StringPartition[x, 1]  ], StringPartition[ x1, 4, 1 ]], True, {1}, 1] + 3

part 2

give a string, find the first sequence of 14 distinct characters, answer the last character's index. (index start at 1)

x1 = "mjqjpqmgbljsphdztnvjfqwrcgsmlb"
x2 = StringPartition[ x1, 14, 1 ]
Position[ Map[ Function[{x}, UnsameQ @@ StringPartition[x, 1]  ], x2], True, {1}, 1] + 13

(* 19 *)