整个走法的题我觉的和陈向东的《GMAT数学高分快速突破》P47/28题一样.方法是:C94. 《GMAT数学高分快速突破》P47/28题: Pat will walk from intersection X to intersection Y along a aoute that is confined to the square graid of four streets and three avenues shoun in the map above . How many routes from X to Y can pat take that have the minimum possible length? map: Av A AvB AvC 4th street ____1____1____1_____Y 3rd street ____1____1____1_____ 2nd street ____1____1____1_____ 1st street X____1____1____1_____ 没有画图,大家凑合看吧,把1串起来代表竖线。 |