.

CS1032/lecture-2023-11-23/nqueens.py

@@ -0,0 +1,18 @@
+def safe(q1, q2):
+    (q1x, q1y) = q1
+    (q2x, q2y) = q2
+    return q1x != q2x and q1y != q2y and abs(q1x - q2x) != abs(q1y - q2y)
+
+def possible_positions(current, n):
+    return ((*current, y) for y in range(n) if all(safe((len(current), y), q) for q in enumerate(current)))
+
+def solutions_r(current, n = 8):
+    if len(current) == n:
+        yield current
+        return
+
+    for pos in possible_positions(current, n):
+        yield from solutions_r(pos, n)
+
+def solutions(n = 8):
+    return solutions_r((), n)