Talk:Shanten: Difference between revisions

Talk:Shanten (view source)

1,093 bytes added , 14 December 2021

1

edit

@@ Line 1: / Line 1: @@
 ==Articles==
 * http://blog.ezyang.com/2014/04/calculating-shanten-in-mahjong/ [[User:KyuuAA|KyuuAA]] ([[User_talk:KyuuAA|Talk:キュウ]]) 17:28, 7 August 2019 (UTC)
+== Possible error in accurate shanten formula ==
+The wiki reports this formula (ignoring the calculations for chiitoitsu and kokushi musou):
+ <nowiki>accurateShanten = 8 - 2 * groups - max(pairs + taatsu, floor(hand.length/3)-groups) - min(1, max(0, pairs + taatsu - (4 - groups)))).</nowiki>
+Let's try to plug in values for a complete regular hand (14 tiles: 4 groups and 1 pair):
+ <nowiki>
+accurateShanten = 8 - 2 * 4 - max(1 + 0, 4 - 4) - min(1, max(0, 1 + 0 - (4 - 4))) =
+- 8 - 1 - 1 =
+                        -2
+</nowiki>
+But -2 makes no sense! I think the correct formula should replace max with min:
+ <nowiki>accurateShanten = 8 - 2 * groups - min(pairs + taatsu, floor(hand.length/3)-groups) - min(1, max(0, pairs + taatsu - (4 - groups)))).</nowiki>
+Now the result is -1 as expected:
+ <nowiki>
+accurateShanten = 8 - 2 * 4 - min(1 + 0, 4 - 4) - min(1, max(0, 1 + 0 - (4 - 4))) =
+- 8 - 0 - 1 =
+                        -1
+</nowiki>
+Let me know if this makes sense. I hope I got right the meaning of the original formula.