1 def A_star_search
 2     q = PriorityQueue()
 3     #优先队列，顺便起到open表的作用
 4     q.put(qnode)
 5     came_from = {}
 6     #came_from为记录拓展过程的链表
 7     cost_so_far = {}
 8     #cost_so_far[p]为起点到节点p目前已知花费
 9     came_from[start_state] = None
10     cost_so_far[start_state] = 0
11 
12     while not q.empty():
13         cur_state = q.get()
14         if cur_state == goal_state:
15             break
16         #假设用邻接表存储，用边权矩阵原理类似
17         for nxt in G.neighbour(cur_state):
18             new_cost = cost_so_far[cur_state] + G.cost(cur_state, nxt)
19             if nxt not in cost_so_far or new_cost < cost_so_far[nxt]
20                 cost_so_far[nxt] = new_cost
21                 priority = new_cost + heuristic(goal_state, nxt)
22                 q.put(qnode(....including "priority", "nxt"))
23                 came_from[nxt] = cur_state
24 
25     return came_from, cost_so_far