python version functional

cell.py

@@ -0,0 +1,29 @@
+class cell:
+    row = []
+    col = []
+    square = []
+    candidates = []
+    is_set = False
+    n = -1
+
+    def __init__(self, n):
+        self.candidates = [1,2,3,4,5,6,7,8,9]
+        self.n = n
+
+    def set(self, n):
+        assert n in self.candidates
+        self.candidates = [n]
+        self._prune(n)
+        self.is_set = True
+
+    def _prune(self, n):
+        for c in self.row:
+            if n in c.candidates:
+                c.candidates.remove(n)
+        for c in self.col:
+            if n in c.candidates:
+                c.candidates.remove(n)
+        for c in self.square:
+            if n in c.candidates:
+                c.candidates.remove(n)
+