@staticmethod
    def _recursive_build(tree_node, s, paths):
        map = tree_node['map']
        moves = map.get_moves()
        for move in moves:
            map_copy = deepcopy(map)
            map_copy.move(move)
            string = AI_Player._map_core_to_str(map_copy.get_core())
            if string in s:
                continue
            tree_node['children'].append( { 'map' : map_copy, 'path' : tree_node['path'] + move[2], 'children' : [] } )
            s.add(string)
        for child in tree_node['children']:
            if child['map'].has_ended():
                paths.append(child['path'])
                continue
            AI_Player._recursive_build(child, s, paths)