Puzzleup 2015 (5) Ten Points - 拼圖

題目網址: http://www.puzzleup.com/2015/
http://www.puzzleup.com/2015/puzzle/?5
答題時限: ８月27日７ＰＭ－比賽結束（約12月16日）
加分時限: ８月27日７ＰＭ－９月１日６：５９ＰＭ

答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　

◆TEN POINTS

You will place 10 points on a paper and you will connect all these points to
each other by lines.

What can be the minimum number of intersections of these lines?

Notes:
- There will be a line between every two points.
- Only two lines can intersect at an intersection point.
- The 10 points themselves will not be considered as intersection points.
- Lines are not required to be straight.

你在紙上點下十個點，將這些點彼此之間用線連接起來。

試問這些線的交點最少有幾個？

註:
- 任兩點之間都有連線。
- 每個交點都僅是兩條線的交點。
- 此十點不算入這些交點。
- 線不必要是直的。

--
LPH [acronym]
= Let Program Heal us
-- New Uncyclopedian Dictionary, Minmei Publishing Co.

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