编辑“︁A 搜索算法”︁（章节）

== 算法步骤 ==
以下是A*算法的伪代码实现：

<syntaxhighlight lang="python">
def A_star_search(start, goal, heuristic):
    open_set = PriorityQueue()
    open_set.put(start, 0)
    came_from = {}  # 记录路径
    g_score = {node: float('inf') for node in graph}
    g_score[start] = 0
    f_score = {node: float('inf') for node in graph}
    f_score[start] = heuristic(start, goal)

    while not open_set.empty():
        current = open_set.get()

        if current == goal:
            return reconstruct_path(came_from, current)

        for neighbor in graph.neighbors(current):
            tentative_g_score = g_score[current] + graph.cost(current, neighbor)
            if tentative_g_score < g_score[neighbor]:
                came_from[neighbor] = current
                g_score[neighbor] = tentative_g_score
                f_score[neighbor] = g_score[neighbor] + heuristic(neighbor, goal)
                if neighbor not in open_set:
                    open_set.put(neighbor, f_score[neighbor])

    return None  # 无路径存在
</syntaxhighlight>