Codeforces Global Round 15
C
Maximize the Intersections
Codeforces
1800
原题
← BD →
翻译中…

On a circle lie $2n$ distinct points, with the following property: however you choose $3$ chords that connect $3$ disjoint pairs of points, no point strictly inside the circle belongs to all $3$ chords. The points are numbered $1, \, 2, \, \dots, \, 2n$ in clockwise order.

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Initially, $k$ chords connect $k$ pairs of points, in such a way that all the $2k$ endpoints of these chords are distinct.

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You want to draw $n - k$ additional chords that connect the remaining $2(n - k)$ points (each point must be an endpoint of exactly one chord).

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In the end, let $x$ be the total number of intersections among all $n$ chords. Compute the maximum value that $x$ can attain if you choose the $n - k$ chords optimally.

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Note that the exact position of the $2n$ points is not relevant, as long as the property stated in the first paragraph holds.

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Input

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The first line contains a single integer $t$ ($1 \le t \le 100$) — the number of test cases. Then $t$ test cases follow.

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The first line of each test case contains two integers $n$ and $k$ ($1 \le n \le 100$, $0 \le k \le n$) — half the number of points and the number of chords initially drawn.

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Then $k$ lines follow. The $i$-th of them contains two integers $x_i$ and $y_i$ ($1 \le x_i, \, y_i \le 2n$, $x_i \ne y_i$) — the endpoints of the $i$-th chord. It is guaranteed that the $2k$ numbers $x_1, \, y_1, \, x_2, \, y_2, \, \dots, \, x_k, \, y_k$ are all distinct.

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Output

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For each test case, output the maximum number of intersections that can be obtained by drawing $n - k$ additional chords.

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Note

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In the first test case, there are three ways to draw the $2$ additional chords, shown below (black chords are the ones initially drawn, while red chords are the new ones):

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image

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We see that the third way gives the maximum number of intersections, namely $4$.

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In the second test case, there are no more chords to draw. Of course, with only one chord present there are no intersections.

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In the third test case, we can make at most one intersection by drawing chords $1-3$ and $2-4$, as shown below:

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image

翻译中…

样例

Input #1
4
4 2
8 2
1 5
1 1
2 1
2 0
10 6
14 6
2 20
9 10
13 18
15 12
11 7
Output #1
4
0
1
14
InputCopy OutputCopy
题目信息
题号
1552C
时间限制
1 s
内存限制
256 MB
标签
组合数学
构造
计算几何
贪心
排序

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