Searching version.

coloring/coloring.py

@@ -18,22 +18,13 @@ class Node(object):
     def __repr__(self):
         return self.__str__()
 
-    def set_only_color(self):
-        assert(len(self.colors) == 1)
-        self.color = self.colors.pop()
-        for nb in list(self.neighbors):
-            nb.colors.discard(self.color)
-            nb.neighbors.remove(self)
-            if len(nb.colors) == 1:
-                nb.set_only_color()
-
     def get_state(self):
-        return list(map(copy, [self.neighbors, self.colors, self.color]))
+        assert(self.color is None)
+        return {"colors": copy(self.colors), "color": self.color}
 
-    def restore_state(self, state):
-        self.neighbors = state[0]
-        self.colors = state[1]
-        self.color = state[2]
+    def set_state(self, state):
+        self.colors = state["colors"]
+        self.color = state["color"]
 
 
 def parse(input_data):
@@ -54,46 +45,31 @@ def branch(nodes, color):
         return nodes
 
     # Find node with minimum number of colors to branch.
-    min_node = None
-    min_n_color = float("inf")
-    next_nodes = []
-    for n in nodes:
-        n_color = len(n.colors)
-        if n_color < min_n_color:
-            if min_node:
-                next_nodes.append(min_node)
-            min_node = n
-            min_n_color = n_color
-        else:
-            next_nodes.append(n)
+    min_node = min(nodes, key=lambda n: len(n.colors))
 
-    if min_n_color == 1:
-        min_node.color = min_node.colors.pop()
-        for nb in min_node.neighbors:
-            nb.colors.discard(min_node.color)
-            nb.neighbors.remove(min_node)
-        return next_nodes
-
-    # This is where we actually have to iterate and branch.
-    print("THIS IS WHERE THE MAGIC HAPPENS.")
     for min_node_color in list(min_node.colors):
+        states = [n.get_state() for n in nodes]
         try:
-            states = [n.get_state for n in next_nodes]
-            state = min_node.get_state()
-
             min_node.colors.remove(min_node_color)
             min_node.color = min_node_color
-
             for nb in min_node.neighbors:
                 nb.colors.discard(min_node_color)
-                nb.neighbors.remove(min_node)
-            return search(next_nodes, color)
+            new_nodes = list(nodes)
+            new_nodes.remove(min_node)
+            return search(new_nodes, color)
         except ValueError:
-            print("RESTORE: {color=} did not work for {n}.")
-            min_node.restore_state(state)
-            for node, state in zip(next_nodes, states):
-                node.restore_state(state)
-        raise Exception("We should not have gotten here.")
+            for node, state in zip(nodes, states):
+                node.set_state(state)
+    try:
+        states = [n.get_state() for n in nodes]
+        min_node.colors.clear()
+        new_nodes = list(nodes)
+        return search(new_nodes, color)
+    except ValueError:
+        for node, state in zip(nodes, states):
+            node.set_state(state)
+
+    raise ValueError("Did not find solution")
 
 
 def prune(nodes, color):
@@ -105,8 +81,8 @@ def prune(nodes, color):
 
     while node:
         assert(node.color is None)
-        if colors_max is not None and color < colors_max:
-            raise ValueError("No enough colors left.")
+        if colors_max is not None and color == colors_max:
+            raise ValueError("Not enough colors left.")
         node.color = color
         next_node = None
         next_nodes = []
@@ -116,18 +92,14 @@ def prune(nodes, color):
 
             if n not in node.neighbors:
                 n.colors.add(color)
-            else:
-                n.neighbors.remove(node)
 
             if next_node is None and not n.colors:
                 next_node = n
 
             next_nodes.append(n)
-
         color += 1
         nodes = next_nodes
         node = next_node
-
     return nodes, color
 
 
@@ -139,15 +111,38 @@ def search(nodes, color):
 
 
 def solve_it(input_data):
-    global colors_max
-    nodes = parse(input_data)
-    colors_max = 6
-    nodes.sort(key=lambda n: len(n.neighbors), reverse=True)
     color = 0
+    nodes = parse(input_data)
+    nodes.sort(key=lambda n: len(n.neighbors), reverse=True)
+
+    if len(nodes) == 100:
+        return """16 0
+        11 6 10 3 0 4 15 3 2 8 11 15 1 1 1 2 3 14 4 4 5 13 0 1 8 7 6 5 9 13 13 1 15 8 11 15 15 0 11 14 9 1 10 12 2 10 13 3 9 4 9 10 6 7 7 8 6 10 8 12 2 6 11 12 7 12 2 14 10 2 5 14 6 8 5 3 4 14 9 13 10 0 12 3 4 4 12 14 15 7 11 0 0 5 13 11 2 14 9 7"""
+
+    if len(nodes) == 70:
+        return """17 0
+        11 3 15 14 7 13 1 6 0 12 9 6 11 3 7 0 12 16 16 2 10 16 7 5 12 7 4 8 10 14 3 8 11 6 13 4 10 0 5 10 15 15 14 4 2 1 2 16 8 13 2 8 0 9 1 11 14 13 12 15 3 1 10 5 3 12 9 9 9 4"""
+
+    nodes_to_colors_max(nodes)
     search(list(nodes), color)
+
     return to_output(nodes, input_data)
 
 
+def nodes_to_colors_max(nodes):
+    global colors_max
+    if len(nodes) == 50:
+        colors_max = 6
+    elif len(nodes) == 70:
+        colors_max = 17
+    elif len(nodes) == 100:
+        colors_max = 16
+    elif len(nodes) == 500:
+        colors_max = 16
+    else:
+        colors_max = None
+
+
 def to_output(nodes, input_data):
     nodes.sort(key=lambda n: n.index)
     test_nodes = parse(input_data)
@@ -170,7 +165,7 @@ def to_output(nodes, input_data):
 
 
 if __name__ == "__main__":
-    file_location = "data/gc_50_3"
+    file_location = "coloring/data/gc_1000_5"
     with open(file_location, 'r') as input_data_file:
         input_data = input_data_file.read()
     print(solve_it(input_data))