使用爬山算法的滑动瓷砖问题

Question

我正在尝试使用爬山算法解决滑动瓷砖问题。我已经编写了代码来打印每个中间步骤，直到到达目标节点，但代码返回的是内存地址。

from copy import deepcopy

class State:
    def __init__(self, state):
        goal_state = [[1, 2, 3], [8, 0, 4], [7, 6, 5]]
        self.state = state
        self.cost = self.calculate_cost(goal_state)


    def calculate_cost(self, goal_state):

        cost = 0

        for i in range(3):
            for j in range(3):
                if self.state[i][j] != goal_state[i][j]:
                    cost += 1

        return cost


    def generate_neighbors(self):
        neighbors = []

        for i in range(3):
            for j in range(3):
                if self.state[i][j] == 0:

                    new_state = deepcopy(self.state)

                    if i >= 0 and i != 2:   #move down
                        new_state[i][j], new_state[i+1][j] = new_state[i+1][j], new_state[i][j]
                        neighbors.append(State(new_state))

                    if i <=2 and i != 0:    #move up
                        new_state[i][j], new_state[i-1][j] = new_state[i-1][j], new_state[i][j]
                        neighbors.append(State(new_state))

                    if j >= 0 and j != 2: # move right
                        new_state[i][j], new_state[i][j+1] = new_state[i][j+1], new_state[i][j]
                        neighbors.append(State(new_state))

                    if j <= 2 and j != 0:   # move left
                        new_state[i][j], new_state[i][j-1] = new_state[i][j-1], new_state[i][j]
                        neighbors.append(State(new_state))


        return neighbors

def hill_climbing(initial_state):

    current_state = initial_state

    while True:
        neighbors = current_state.generate_neighbors()
        best_neighbor = min(neighbors, key = lambda state: state.cost)

        if best_neighbor.cost <= current_state.cost:
            print(best_neighbor)
            break

        print(current_state)
        current_state = best_neighbor


initial_state = State([[2, 0, 3], [1, 8, 4], [7, 6, 5]])

hill_climbing(initial_state)

输出：

<__main__.State object at 0x0000021FE103FEE0>

Answer 1

Python 不知道如何打印你的

State

对象，因此它只返回一个内存地址

您可以向

__repr__

类添加

State

方法，该方法将返回类状态的格式化字符串。这是一个示例（您需要添加到您的班级）：

def __repr__(self):
    # Create a readable string for the state
    return '\n'.join([' '.join(map(str, row)) for row in self.state])

__repr__

方法将状态格式化为字符串，其中每行都在新行上，数字之间用空格分隔。一旦你打印了一个

State

对象（就像现在一样），它将显示一个漂亮的格式化字符串而不是内存地址

这里有 2 个相关的 stackoverflow 讨论也很有帮助：one 和 two