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POJ 3668 Game of Lines C语言版

POJ题解 Slyar 62浏览 0评论

文章作者:姜南(Slyar) 文章来源:Slyar Home (www.slyar.com) 转载请注明,谢谢合作。

Description

Farmer John has challenged Bessie to the following game: FJ has a board with dots marked at N (2 ≤ N ≤ 200) distinct lattice points. Dot i has the integer coordinates Xi and Yi (-1,000 ≤ Xi ≤ 1,000; -1,000 ≤ Yi ≤ 1,000).

Bessie can score a point in the game by picking two of the dots and drawing a straight line between them; however, she is not allowed to draw a line if she has already drawn another line that is parallel to that line. Bessie would like to know her chances of winning, so she has asked you to help find the maximum score she can obtain.

Input

* Line 1: A single integer: N
* Lines 2..N+1: Line i+1 describes lattice point i with two space-separated integers: Xi and Yi.

Output

* Line 1: A single integer representing the maximal number of lines Bessie can draw, no two of which are parallel.

Sample Input

4
-1 1
-2 0
0 0
1 1

Sample Output

4

Slyar:题目大意就是求N个点最多确定多少条互不平行的直线。

算法很简单,挨个求斜率,注意考虑斜率不存在的情况。对斜率排序后统计有多少种不同的斜率即可。

这道题我因为double的精度问题WA了很多次,双精度是不能对0直接判等的,还有就是对double排序的qsort的cmp函数一定也要注意精度问题...

转载请注明:Slyar Home » POJ 3668 Game of Lines C语言版

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网友最新评论 (2)

  1. 不能和0比较,可以和0.0比较啊!
    匿名6年前 (2010-10-13)回复
  2. 这一个礼拜我都不用来你博客了……全是鸟语……
    Jutoy8年前 (2009-04-21)回复