买彩票

野菜花 · 发表于 2006-1-25 01:42:37

某种彩票要填50个数字(1~50的一个排列) ，只要一个数字对就可得奖，问至少要买多少张肯定能得奖，为什么?

ob · 发表于 2006-2-3 03:08:04

Another way to arrange the number. But it still does not satisfy the 26 tickets retuirement.

1, 2, 3, .............................50
2, 3, 4, ........................50, 1
3, 4, 5,.....................50, 1, 2
...........................................
25, 26, ...........50, 1, ........24
26, 27,.......50, 1, 2, .........25

野菜花 · 发表于 2006-1-26 17:36:21

the method is right, almost there!

ob · 发表于 2006-1-26 08:51:06

Initially, I thought to make a matrx of 25x50. Select elements (number 1 to 25) and make the left 25x25 to be such a matrix that each column and each row contains 1 to 25. Similarly make the right side 25x25 matrix by using 26 to 50. This way, there will be at least one number in set #26 matches a number in the 25x50 matrix.

But I test it and it is not right. I need to think more

野菜花 · 发表于 2006-1-25 22:17:20

you explain why?

ob · 发表于 2006-1-25 21:58:01

26?

野菜花 · 发表于 2006-1-25 18:54:32

fewer

ob · 发表于 2006-1-25 08:01:58

Then buy 50. Write the first number of the tickets from 1 to 50.

I wonder whether I buy less to win the prize

野菜花 · 发表于 2006-1-25 03:18:58

50个数字必须是不同的，是1~50的一个排列

ob · 发表于 2006-1-25 03:00:05

Buy one is enough. Just need to make sure all the numbers are the same. Then definetly it will match one number in the sequence.

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回复：50个数字必须是不同的，是1~50的一个排列[;)]

50个数字必须是不同的，是1~50的一个排列[;)]

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