回复：趁两高手在,再请教两个题目...最要命的是我连题目都没看懂

question 1.
Of the three-digit integers greater than 700
means digits from 701 to 999.

Break 701 to 999 into 3 parts as
part1: 701 to 799
part2: 800 to 899
part3: 900 to 999

Working on part 1,
1) for the range of 701 to 710
701, 702, 703, 704, 705, 706, 707, 708, 709, 710
you find 707 is the one, which are equal to each other and the remaining digit different from the other two.

2. for the range 711 to 720, you have 711 and 717
3. for the range 721 to 730, you have 722 and 727
4. for the range 731 to 740, you have 733 and 737
5. for the range 741 to 750, you have 744 and 747
6. for the range 751 to 760, you have 755 and 757
7. for the range 761 to 770, you have 766 and 767, 770
8. for the range 771 to 780, you have
771,772,773,774,775,776,778,779
9. for the range 781 to 790, you have 788 and 787
10 for the range 791 to 800, you have 800 and 797,799

So for part 1,you have 27

所有跟帖： 

• 非常清楚,谢谢 -陶陶乐，乐陶陶- ♀ (41 bytes) () 12/06/2009 postreply 13:10:42

• 老任是个好教授 -bearsback- ♂ (28 bytes) () 12/06/2009 postreply 14:13:08

• 回复：老任是个好教授 -not.me- ♀ (0 bytes) () 12/06/2009 postreply 15:24:15

• 连头发丝都数尽了,也没做出来.真后悔当年只开除热机没去下围棋。 -not.me- ♀ (0 bytes) () 12/06/2009 postreply 15:28:57

• 无语 -bearsback- ♂ (26 bytes) () 12/06/2009 postreply 16:00:33

• 你真聪明。我还是很迷糊。任老师是我们数学系的退休教授。 -not.me- ♀ (0 bytes) () 12/06/2009 postreply 15:31:14

• 原来如此,今天真幸运 -陶陶乐，乐陶陶- ♀ (0 bytes) () 12/06/2009 postreply 15:35:33

• 一点不错。任我为不光数学好，武功也好。好好拜山头学艺吧。 -not.me- ♀ (0 bytes) () 12/06/2009 postreply 15:42:29

• 那一定的... -陶陶乐，乐陶陶- ♀ (0 bytes) () 12/06/2009 postreply 15:59:15

• 也拜这位 NOT。ME 女侠 能学到不少东西 -23731241- ♂ (0 bytes) () 12/06/2009 postreply 16:01:22

• 其实,这里真正的高人是上面这为数字先生.你能看懂这写数字的玄机吗？ -not.me- ♀ (0 bytes) () 12/06/2009 postreply 16:14:34

• 看不懂,本来对数字就没天分... -陶陶乐，乐陶陶- ♀ (0 bytes) () 12/06/2009 postreply 16:21:57

• haha，俺不敢说，说了他会把我撕成碎片的：） -not.me- ♀ (0 bytes) () 12/06/2009 postreply 16:29:17

• 我探访多年楞没找到解。不怕，说吧，姐BACK UP你。 -念亲- ♀ (66 bytes) () 12/06/2009 postreply 19:05:00

• 我只开个头:饿-死俺-气-死俺-1-2-4-1后面４个自己想吧：） -not.me- ♀ (0 bytes) () 12/06/2009 postreply 19:17:44

• 密码，要骂就骂２姐吧，不怪我。haha -not.me- ♀ (0 bytes) () 12/06/2009 postreply 19:19:07

• 唉，你这个丫头片子... -念亲- ♀ (160 bytes) () 12/06/2009 postreply 19:43:01

• haha, ２姐说的更逗。我学一会儿去了。 -not.me- ♀ (0 bytes) () 12/06/2009 postreply 19:48:57

• 88 -念亲- ♀ (0 bytes) () 12/06/2009 postreply 19:54:14

• 真厉害！我想了７个小时，还是不会做。 -not.me- ♀ (0 bytes) () 12/06/2009 postreply 15:32:43