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Sometimes some mathematical results are hard to believe. One of the common problems is the birthday paradox. Suppose you are in a party where there ar 阅读全文
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Description There are n distinct points in the plane, given by their integer coordinates. Find the number of parallelograms whose vertices lie on thes 阅读全文
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Problem Description Once again, James Bond is fleeing from some evil people who want to see him dead. Fortunately, he has left a bungee rope on a near 阅读全文
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Fox Ciel is playing a mobile puzzle game called "Two Dots". The basic levels are played on a board of size n × m cells, like this: Each cell contains 阅读全文
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Euler is a well-known matematician, and, among many other things, he discovered that the formula n 2 + n + 41 produces a prime for 0 ≤ n < 40. For n = 阅读全文