用python写出TSP问题的代码

以下是一个简单的 Python 代码，用于解决旅行商问题（TSP）：

import itertools

def tsp(cities):
    shortest_path = None
    shortest_distance = float('inf')
    for path in itertools.permutations(cities):
        distance = sum(distance_between(path[i], path[i+1]) for i in range(len(path)-1))
        if distance < shortest_distance:
            shortest_distance = distance
            shortest_path = path
    return shortest_path, shortest_distance

def distance_between(city1, city2):
    # 计算两个城市之间的距离
    pass

# 示例用法
cities = ['A', 'B', 'C', 'D']
shortest_path, shortest_distance = tsp(cities)
print('最短路径:', shortest_path)
print('最短距离:', shortest_distance)

请注意，此代码仅用于演示目的，实际上需要实现 `distance_between` 函数来计算两个城市之间的距离。