一个旅行商要去N个城市旅行，这N个城市中，任意两个城市之间都有一条路径，路径的长度按照两个城市之间的直线距离计算。找出一条路径，使得旅行商从A城市出发经过所有的城市再回到A城市，所经过的路径最短，每个城市不能重复旅行。-A traveling salesman to go to N-city travel, N cities, arbitrarily between the two cities have a path, the path length calculated in accorda