a*算法求解八数码问题c

以下是使用A*算法求解八数码问题的Python代码示例：

from queue import PriorityQueue

# 计算曼哈顿距离
def manhattan_distance(state):
    distance = 0
    for i in range(3):
        for j in range(3):
            if state[i][j] != 0:
                distance += abs(i - (state[i][j] - 1) // 3) + abs(j - (state[i][j] - 1) % 3)
    return distance

# A*算法求解八数码问题
def solve_puzzle(start_state, goal_state):
    # 定义open表和close表
    open_queue = PriorityQueue()
    open_queue.put((manhattan_distance(start_state), start_state, 0))
    close_set = set()

    while not open_queue.empty():
        # 取出open表中f值最小的节点
        f, state, steps = open_queue.get()
        if state == goal_state:
            return steps
        close_set.add(str(state))

        # 扩展节点
        zero_row, zero_col = 0, 0
        for i in range(3):
            for j in range(3):
                if state[i][j] == 0:
                    zero_row, zero_col = i, j
                    break

        for i, j in [(0, 1), (0, -1), (1, 0), (-1, 0)]:
            new_row, new_col = zero_row + i, zero_col + j
            if 0 <= new_row < 3 and 0 <= new_col < 3:
                new_state = [row[:] for row in state]
                new_state[zero_row][zero_col], new_state[new_row][new_col] = new_state[new_row][new_col], new_state[zero_row][zero_col]
                if str(new_state) not in close_set:
                    open_queue.put((manhattan_distance(new_state) + steps + 1, new_state, steps + 1))

    return -1 # 无解情况

# 测试
start_state = [[2, 8, 3], [1, 6, 4], [7, 0, 5]]
goal_state = [[1, 2, 3], [8, 0, 4], [7, 6, 5]]
steps = solve_puzzle(start_state, goal_state)
if steps == -1:
    print("无解")
else:
    print("最少需要%d步" % steps)