#P10876. [COTS 2022] 点组 Točkice

    ID: 12347 远端评测题 1000ms 500MiB 尝试: 0 已通过: 0 难度: 8 上传者: 标签>博弈论2022O2优化凸包COCI(克罗地亚)

[COTS 2022] 点组 Točkice

Background

Translated from Izborne Pripreme 2022 (Croatian IOI/CEOI Team Selection) D2T3. 1s,0.5G\texttt{1s,0.5G}

Problem Description

There are NN points (xi,yi)(x_i,y_i) on the plane, and no three points are collinear. Two players take turns. In each move, a player chooses two points and connects them with a line segment, with the requirement that it does not intersect any previous segment at a non-endpoint. The player who cannot make a move loses. Determine whether the first player wins or the second player wins.

Input Format

The first line contains an integer NN

The next NN lines each contain two integers xi,yix_i,y_i

Output Format

If A (the first player) wins, output Alenka; otherwise output Bara

4
0 0
0 10
10 0
10 10
Alenka
5
2 1
1 3
6 4
3 5
5 2
Alenka
4
4 2
2 4
2 2
1 1
Bara

Hint

For 100%100\% of the testdata, it is guaranteed that:

  • 1N1051\le N\le 10^5
  • 1xi,yi1061\le x_i,y_i\le 10^6
  • No three points are collinear.
Subtask ID Score NN\le
11 1313 77
22 1717 300300
33 2121 10001\, 000
44 4949 10510^5

Translated by ChatGPT 5