From 8c7809d024e85d0a8acfb794a4db41b0e4bc13e6 Mon Sep 17 00:00:00 2001
From: Shinya Sato <shinnya.sato@gmail.com>
Date: Mon, 2 May 2022 09:49:01 +0900
Subject: v0.8.2-1

---
 comparison/Haskell/msort-260000.hs | 51 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 comparison/Haskell/msort-260000.hs

(limited to 'comparison/Haskell/msort-260000.hs')

diff --git a/comparison/Haskell/msort-260000.hs b/comparison/Haskell/msort-260000.hs
new file mode 100644
index 0000000..49cae3c
--- /dev/null
+++ b/comparison/Haskell/msort-260000.hs
@@ -0,0 +1,51 @@
+{-
+https://stackoverflow.com/questions/25839939/understanding-merge-sort-in-ml
+-}
+import System.Random
+
+mysplit [] = ([], [])
+mysplit [a] = ([a], [])
+mysplit (a:b:cs) = (a:m, b:n)
+  where
+    (m,n) = mysplit cs
+    
+merge ([], ys) = ys
+merge (xs, []) = xs
+merge (x:xs, y:ys)
+  | x<y = x:merge(xs, y:ys)
+  | otherwise = y:merge(x:xs, ys)
+
+msort [] = []
+msort [a] = [a]
+msort [a,b]
+  | a<b = [a,b]
+  | otherwise = [b,a]
+msort xs = merge (msort m, msort n)
+  where
+    (m,n) = mysplit xs
+
+{-
+main = print $ msort [3,2,8,5]
+-}
+
+
+randomList :: Int -> IO([Int])
+randomList 0 = return []
+randomList n = do
+  r  <- randomRIO (1,10000)
+  rs <- randomList (n-1)
+  return (r:rs)
+
+
+validation [] = True
+validation (x:xs) = validation_cons x xs
+validation_cons x [] = True
+validation_cons x (y:ys) =
+  if x<=y then validation_cons y ys
+  else False
+
+
+main = do
+  list <- randomList 260000
+  let sorted = msort list
+  print (validation sorted)
-- 
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