From 02a84743ddf5c8c27a36c4d5a20eaf3cd2a9aff4 Mon Sep 17 00:00:00 2001
From: Shinya Sato <shinnya.sato@gmail.com>
Date: Sun, 28 Aug 2022 20:40:57 +0900
Subject: Update for n-queens

---
 comparison/OCaml/Makefile    |  5 ++++-
 comparison/OCaml/nqueen12.ml | 23 +++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 comparison/OCaml/nqueen12.ml

(limited to 'comparison/OCaml')

diff --git a/comparison/OCaml/Makefile b/comparison/OCaml/Makefile
index 9db7726..18c1eda 100644
--- a/comparison/OCaml/Makefile
+++ b/comparison/OCaml/Makefile
@@ -1,7 +1,7 @@
 CC      = ocamlopt
 CFLAGS  = 
 BENCHMARK  = bash ../tools/sptest_commands.sh
-TARGET  = ack3_11 fib38 bsort20000 isort20000 qsort260000 msort260000
+TARGET  = nqueen12 ack3_11 fib38 bsort20000 isort20000 qsort260000 msort260000
 LOG = log.txt
 
 
@@ -12,6 +12,9 @@ all: $(LOG)
 $(LOG): $(TARGET)
 	$(BENCHMARK) $(TARGET)
 
+nqueen12: nqueen12.ml
+	$(CC) $(CFLAGS) $< -o $@
+
 ack3_11: ack3_11.ml
 	$(CC) $(CFLAGS) $< -o $@
 
diff --git a/comparison/OCaml/nqueen12.ml b/comparison/OCaml/nqueen12.ml
new file mode 100644
index 0000000..fc56542
--- /dev/null
+++ b/comparison/OCaml/nqueen12.ml
@@ -0,0 +1,23 @@
+let rec member x alist =
+  match alist with
+    []    -> false
+  | y::ys -> if x=y then true else (member x ys);;
+
+let rec threat k m alist =
+  match alist with
+    []    -> false
+  | x::xs ->  if (k = x-m) || (k = m-x) then true
+              else (threat (k+1) m xs);;
+
+let rec queen1 m b n =
+  match m with
+    0 -> []
+  | m ->
+    if (member m b) || (threat 1 m b) then (queen1 (m-1) b n)
+    else if (List.length b) = (n-1) then [m::b]@(queen1 (m-1) b n)
+         else (queen1 n (m::b) n) @ (queen1 (m-1) b n);;
+
+let queen n = queen1 n [] n;;
+
+let n = 12;;
+let () = print_int (List.length (queen n));
-- 
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