From fa1bf6c2eac1c9f7969ff29504c9f51b9ba48008 Mon Sep 17 00:00:00 2001
From: Determinant <ted.sybil@gmail.com>
Date: Mon, 29 May 2017 01:11:20 -0400
Subject: finish vol 3

---
 21-28/25.hs | 9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 21-28/25.hs

(limited to '21-28/25.hs')

diff --git a/21-28/25.hs b/21-28/25.hs
new file mode 100644
index 0000000..4306ae1
--- /dev/null
+++ b/21-28/25.hs
@@ -0,0 +1,9 @@
+import System.Random
+rndPermu :: [a] -> IO [a]
+
+rndPermu l = d l (length l)
+    where
+        d l@(x:xs) n | n > 0 = do i <- getStdRandom $ randomR (0, (length l) - 1)
+                                  r <- d (take i l ++ drop (i + 1) l) (n - 1)
+                                  return (l!!i:r)
+        d _ _ = return []
-- 
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