AtCoder Beginner Contest 157
F
Yakiniku Optimization Problem
AtCoder
⌀ 2525
原题
← E→
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Problem Statement

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Takahashi wants to grill $N$ pieces of meat on a grilling net, which can be seen as a two-dimensional plane. The coordinates of the $i$-th piece of meat are $\left(x_i, y_i\right)$, and its hardness is $c_i$.

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Takahashi can use one heat source to grill the meat. If he puts the heat source at coordinates $\left(X, Y\right)$, where $X$ and $Y$ are real numbers, the $i$-th piece of meat will be ready to eat in $c_i \times \sqrt{\left(X - x_i\right)^2 + \left(Y-y_i\right)^2}$ seconds.

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Takahashi wants to eat $K$ pieces of meat. Find the time required to have $K$ or more pieces of meat ready if he put the heat source to minimize this time.

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Constraints

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  • All values in input are integers.
  • $1 \leq N \leq 60$
  • $1 \leq K \leq N$
  • $-1000 \leq x_i , y_i \leq 1000$
  • $\left(x_i, y_i\right) \neq \left(x_j, y_j\right) \left(i \neq j \right)$
  • $1 \leq c_i \leq 100$
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Input

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Input is given from Standard Input in the following format:

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N K
x_1 y_1 c_1
\vdots
x_N y_N c_N

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Output

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Print the answer.

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It will be considered correct if its absolute or relative error from our answer is at most $10^{-6}$.

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样例

Input #1
4 3
-1 0 3
0 0 3
1 0 2
1 1 40
Output #1
2.4
If we put the heat source at $\left(-0.2, 0\right)$, the $1$-st, $2$-nd, and $3$-rd pieces of meat will be ready to eat within $2.4$ seconds. This is the optimal place to put the heat source.
Input #2
10 5
-879 981 26
890 -406 81
512 859 97
362 -955 25
128 553 17
-885 763 2
449 310 57
-656 -204 11
-270 76 40
184 170 16
Output #2
7411.2252
题目信息
题号
abc157_f
时间限制
2 s
内存限制
1024 MB

题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。