tasks a-s

Task/N-queens-problem/Python/n-queens-problem-3.py

@@ -0,0 +1,17 @@
+# From: http://wiki.python.org/moin/SimplePrograms, with permission from the author, Steve Howell
+BOARD_SIZE = 8
+
+def under_attack(col, queens):
+    return col in queens or \
+           any(abs(col - x) == len(queens)-i for i,x in enumerate(queens))
+
+def solve(n):
+    solutions = [[]]
+    for row in range(n):
+        solutions = [solution+[i+1]
+                       for solution in solutions
+                       for i in range(BOARD_SIZE)
+                       if not under_attack(i+1, solution)]
+    return solutions
+
+for answer in solve(BOARD_SIZE): print(list(enumerate(answer, start=1)))