哥尼斯堡的“七桥问题”，哥尼斯堡是位于普罗格河上的一座城市，包含两个岛屿及连接他们的七座桥，问可否走出这样的七座桥，而且每桥只走一次-Konigsberg' s " Seven Bridges problem,"　Konigsberg is a city located on the river progreso, contains two islands and seven bridges connecting them, asking whether we could out of this seven bridges, and each bridge only once away