Update for n-queens

1 files changed, 27 insertions, 0 deletions

diff --git a/comparison/Python/nqueen-12.py b/comparison/Python/nqueen-12.py
new file mode 100644
index 0000000..494131f
--- /dev/null
+++ b/comparison/Python/nqueen-12.py
@@ -0,0 +1,27 @@
+def threat(k, m, alist):
+    if alist == []:
+        return False
+    else:
+        x = alist[0]        
+        if (k == x-m) or (k == m-x):
+            return True
+        else:
+            return threat(k+1, m, alist[1:])
+        
+def queen1(m, b, n):
+    if m == 0:
+        return []
+    else:
+        if (m in b) or threat(1, m, b):
+            return queen1(m-1, b, n)
+        elif len(b) == n-1:
+            return [[m]+b] + (queen1(m-1, b, n))
+        else:
+            return queen1(n, [m]+b, n) + (queen1(m-1, b, n))
+
+
+def queen(n):
+    return queen1(n,[],n)
+
+n=12
+print(len(queen(12)))