问题　图 1和图 2是某城市的两个部分街道图 ,如果从A处走到B处 (只能由北到南 ,由西向东 ) ,那么在图 1和图 2中分别有多少种不同的走法 ?图 1图 2　　上述问题称为“横纵线路图”问题 .“横纵线路图”是数学中的一类有趣的问题 ,图 1中为矩形“横纵线路图” ,图 2是阶梯“横? Problem Figure 1 and Figure 2 are two partial street maps of a city. If you walk from A to B (only from north to south and from west to east), then how many different differences exist in Figure 1 and Figure 2 Figure 1 Figure 2 The above problem is called the “horizontal and vertical circuit diagram.” “Horizontal and vertical circuit diagram” is an interesting class of mathematics problems, Figure 1 for the rectangular “horizontal and vertical circuit diagram,” Figure 2 Is the ladder "horizontal?