From 787dc13c837f0955fbd85b8f26a05d720d361333 Mon Sep 17 00:00:00 2001
From: Shinya Sato <shinnya.sato@gmail.com>
Date: Sun, 24 Oct 2021 23:04:45 +0900
Subject: Upload the comparison directory

---
 comparison/Haskell/msort-800000.hs | 45 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 comparison/Haskell/msort-800000.hs

(limited to 'comparison/Haskell/msort-800000.hs')

diff --git a/comparison/Haskell/msort-800000.hs b/comparison/Haskell/msort-800000.hs
new file mode 100644
index 0000000..eb1a24d
--- /dev/null
+++ b/comparison/Haskell/msort-800000.hs
@@ -0,0 +1,45 @@
+{-
+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)
+
+
+
+main = do
+  list <- randomList 800000
+  let sorted = msort list
+  print (take 10 sorted)
+
+
-- 
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