Dears，求教OG11绿皮的第54题： IN the table above, what is the least number of table entries that are needed to show the mileage between each city and each of the other five cities? A,15 B,1 C,5 D,0 E,6 答案是A。。。。
It just asks you to find all the different pairs among 6 unique entries. So you have 6 candidates for the #1 position and 5 candidates for the #2 position of the pair. Since you overcounted the number of possible pairs by two ( AB and BA are the same pair), so you need to divide the product of 6*5 by 2.
Just look the picture I used for my name. It's a newly wed couple. Does it matter to choose the bride first or the groom first for the same couple? No. You end up with the same pair! So when choosing by position 1 and position 2 for a pair, you overcount the number of pairs by two.
Just look the picture I used for my name. It's a newly wed couple. Does it matter to choose the bride first or the groom first for the same couple? No. You end up with the same pair! So when choosing by position 1 and position 2 for a pair, you overcount the number of pairs by two.
-- by 会员 sdcar2010 (2011/6/11 11:28:27)
哈哈，sdcar牛牛好会举例子啊，还特意换了个头像。。。 这题我觉得跟the least number没关系。不知大家怎么想的？ 是说有六个city, 每个city和其他五个city都有table entry，问一共有多少table entries 所以就是5×6，但是由于AB配对和BA配对其实是一种情况，所以要除以二
It just asks you to find all the different pairs among 6 unique entries. So you have 6 candidates for the #1 position and 5 candidates for the #2 position of the pair. Since you overcounted the number of possible pairs by two ( AB and BA are the same pair), so you need to divide the product of 6*5 by 2.
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发表于 2011-6-10 10:08:48
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