数据结构农夫过河问题
时间: 2023-12-30 12:23:46 浏览: 37
农夫过河问题可以使用图的数据结构来解决。每个节点表示农夫、狼、羊和白菜在不同的位置,边表示农夫的移动。为了避免狼吃羊或羊吃白菜的情况发生,需要添加一些限制条件。
以下是一个可能的解决方案的示例代码:
```python
from queue import Queue
# 定义农夫过河问题的状态类
class State:
def __init__(self, farmer, wolf, goat, cabbage, boat):
self.farmer = farmer
self.wolf = wolf
self.goat = goat
self.cabbage = cabbage
self.boat = boat
def is_valid(self):
# 检查是否有不合法的状态
if self.wolf == self.goat and self.farmer != self.wolf:
return False
if self.goat == self.cabbage and self.farmer != self.goat:
return False
return True
def is_goal(self):
# 检查是否达到目标状态
return self.farmer == 'N' and self.wolf == 'N' and self.goat == 'N' and self.cabbage == 'N'
def get_next_states(self):
# 获取下一个可能的状态
next_states = []
if self.farmer == self.boat:
# 农夫在当前岸边
if self.farmer == 'N':
next_states.append(State('S', self.wolf, self.goat, self.cabbage, 'S'))
else:
next_states.append(State('N', self.wolf, self.goat, self.cabbage, 'N'))
else:
# 农夫在对岸
if self.wolf == self.boat:
next_states.append(State(self.farmer, 'N', self.goat, self.cabbage, 'N'))
else:
next_states.append(State(self.farmer, 'S', self.goat, self.cabbage, 'S'))
if self.goat == self.boat:
next_states.append(State(self.farmer, self.wolf, 'N', self.cabbage, 'N'))
else:
next_states.append(State(self.farmer, self.wolf, 'S', self.cabbage, 'S'))
if self.cabbage == self.boat:
next_states.append(State(self.farmer, self.wolf, self.goat, 'N', 'N'))
else:
next_states.append(State(self.farmer, self.wolf, self.goat, 'S', 'S'))
return [state for state in next_states if state.is_valid()]
# 使用广度优先搜索算法解决农夫过河问题
def solve():
start_state = State('S', 'S', 'S', 'S', 'S')
if start_state.is_goal():
return [start_state]
visited = set()
queue = Queue()
queue.put([start_state])
while not queue.empty():
path = queue.get()
current_state = path[-1]
for next_state in current_state.get_next_states():
if next_state.is_goal():
return path + [next_state]
if next_state not in visited:
visited.add(next_state)
queue.put(path + [next_state])
return None
# 打印解决方案
solution = solve()
if solution:
for state in solution:
print(f"农夫: {state.farmer}, 狼: {state.wolf}, 羊: {state.goat}, 白菜: {state.cabbage}, 船: {state.boat}")
else:
print("无解")
```