求第 $k$ 小角度可以二分。二分一个角度 $\theta$，我们需要检查有多少对点的连线角度在区间 $[0,\theta)$ 中，这其实是一个二维偏序，排序加树状数组可以在 $O(n\log n)$ 时间解决。总时间复杂度 $O(n\log n\log (1/\epsilon))$。
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Discussion #140 for Problem #7229. Lines
Type: Editorial
Status: Open
Posted by: jiangly
Posted at: 2025-12-12 23:30:47
Last updated: 2025-12-12 23:30:50
题解
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