用1,2,3三个数字组成六位数,若每个数字用两次,相邻位不允许用相同的数字.(1)试写出四个符合上述条
(1)以1开头的数有121323 131232 123123 123132 132123 132132 123213 132312 132321 123231 等10个数; (2)121323,131232,123123,123132,121323,121332,132123,132132,123213,132312,213123,213132,312123,312132,212313,213213,312312,313212,213231,312321,231213,231312,321213,321312,231231,231321,321231,321321,232131,323121则***30个符合条件的六位数. |