Yes there is a Chapter 0. There is a little bit of introductory stuff we need to talk about before we set you loose on Ruby. You wouldn t want to get psyched about a new gadget, get it home, and then figure out you need batteries, a grapefrui

　给定一个N*N 的方形网格，设其左上角为起点◎，坐标为（1，1），X 轴向右为正，Y 轴向下为正，每个方格边长为1。一辆汽车从起点◎出发驶向右下角终点▲，其坐标为（N， N）。在若干个网格交叉点处，设置了油库，可供汽车在行驶途中加油。汽车在行驶过程中应遵守如下规则： 　　求汽车从起点出发到达终点的一条所付费用最少的行驶路线。-Given an N* N square grid, set the upper left corner as a starting point ◎, c