problem 122, seventh, got 'Time Limit Exceeded on test 22 750ms 2583 kb;

 - find_node_outside_path: start from the unvisited nodes, find the node that its child is visited.
problem 122, got 'Time Limit Exceeded on test 7 750ms	907kb'
 - path:represent by array-list
problem 122,got 'Time Limit Exceeded on test 10 	515 ms	1887 kb'
i cannot say anything
problem 122, got 'Time Limit Exceeded on test 10 	515 ms	1823 kb'
 - delete array pre, use single list to represent path.
problem 122, got 'Time Limit Exceeded on test 13 750ms	1827kb'
 - delte some functions, move them to function main;
Merge branch 'find_node_outside_path' into path_list

Conflicts:
	122/sgu2.cpp

problem 122, some changes on sgu2.cpp, noting important