python制作一个框架,可用BFS DFS与A*三种方法解决九宫重排问题,要求初始状态和最终状态由自己决定
时间: 2024-02-09 18:08:40 浏览: 103
三种方法实现的九宫重排程序
好的,我可以为您解答这个问题。首先,您需要了解九宫重排问题的规则和定义。九宫重排是一种经典的智力游戏,游戏目标是将一个 3*3 的方格中的数字 1 到 8 排列成正确的顺序,空格表示为 0。每次可以将 0 所在的格子与上下左右相邻的数字交换位置。下面是一个例子:
```
2 8 3
1 0 4
7 6 5
```
在这个例子中,0 可以与 2、1、4 和 6 进行交换,但不能与 8、3、7 和 5 进行交换。最终的正确状态是:
```
1 2 3
8 0 4
7 6 5
```
接下来,我们可以使用 Python 编写一个九宫重排的框架,可以使用 BFS、DFS 和 A* 算法来解决问题。我们可以定义一个类来表示每个状态,其中包含以下属性:
- state:表示当前的状态矩阵。
- parent:表示当前状态的父状态。
- action:表示从父状态到当前状态的操作。
- depth:表示当前状态的深度。
下面是一些示例代码,展示如何使用 BFS、DFS 和 A* 算法来解决九宫重排问题。这些代码只是示例,需要您进行修改和扩展,以满足您的具体需求。
```python
class State:
def __init__(self, state, parent=None, action=None, depth=0):
self.state = state
self.parent = parent
self.action = action
self.depth = depth
def __eq__(self, other):
return self.state == other.state
def __hash__(self):
return hash(str(self.state))
def __str__(self):
return str(self.state)
def get_successors(self):
successors = []
for i in range(3):
for j in range(3):
if self.state[i][j] == 0:
if i > 0:
new_state = [row[:] for row in self.state]
new_state[i][j], new_state[i-1][j] = new_state[i-1][j], new_state[i][j]
successors.append(State(new_state, self, 'up', self.depth+1))
if j > 0:
new_state = [row[:] for row in self.state]
new_state[i][j], new_state[i][j-1] = new_state[i][j-1], new_state[i][j]
successors.append(State(new_state, self, 'left', self.depth+1))
if i < 2:
new_state = [row[:] for row in self.state]
new_state[i][j], new_state[i+1][j] = new_state[i+1][j], new_state[i][j]
successors.append(State(new_state, self, 'down', self.depth+1))
if j < 2:
new_state = [row[:] for row in self.state]
new_state[i][j], new_state[i][j+1] = new_state[i][j+1], new_state[i][j]
successors.append(State(new_state, self, 'right', self.depth+1))
return successors
def is_goal(self, goal_state):
return self.state == goal_state
def bfs(start_state, goal_state):
queue = [start_state]
visited = set()
while queue:
state = queue.pop(0)
if state.is_goal(goal_state):
return state
visited.add(state)
for successor in state.get_successors():
if successor not in visited and successor not in queue:
queue.append(successor)
def dfs(start_state, goal_state):
stack = [start_state]
visited = set()
while stack:
state = stack.pop()
if state.is_goal(goal_state):
return state
visited.add(state)
for successor in state.get_successors()[::-1]:
if successor not in visited and successor not in stack:
stack.append(successor)
def heuristic(state, goal_state):
count = 0
for i in range(3):
for j in range(3):
if state[i][j] != goal_state[i][j]:
count += 1
return count
def astar(start_state, goal_state):
queue = [(heuristic(start_state.state, goal_state), start_state)]
visited = set()
while queue:
state = queue.pop(0)[1]
if state.is_goal(goal_state):
return state
visited.add(state)
for successor in state.get_successors():
if successor not in visited and successor not in [q[1] for q in queue]:
queue.append((heuristic(successor.state, goal_state) + successor.depth, successor))
queue.sort()
# Example usage
start_state = State([[2, 8, 3], [1, 0, 4], [7, 6, 5]])
goal_state = State([[1, 2, 3], [8, 0, 4], [7, 6, 5]])
bfs_result = bfs(start_state, goal_state)
dfs_result = dfs(start_state, goal_state)
astar_result = astar(start_state, goal_state)
print('BFS solution:', bfs_result.action_sequence())
print('DFS solution:', dfs_result.action_sequence())
print('A* solution:', astar_result.action_sequence())
```
在这个示例代码中,我们定义了三个函数,分别使用 BFS、DFS 和 A* 算法来解决九宫重排问题。在这些函数中,我们创建了一个起始状态和一个目标状态,并使用 State 类来表示这些状态。然后我们使用不同的算法来搜索状态空间,并找到从起始状态到目标状态的最短路径。最后,我们打印出每个算法的解决方案。
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