旅行商问题：某售货员要到若干城市去推销商品，已知各城市之间的路程（或旅费）。他要选定一条从驻地出发，经过每个城市一遍，最后回到驻地的路线，使总的路程（或旅费）最小。-Traveling salesman problem: a number of sales going to the city to sell goods, known distance between cities (or passage). He selected one from a resident, goes throug