题目描述 The Department of National Defence (DND) wishes to connect several northern outposts using a wireless network. Two communication technologies are available: 1. Radio Transceivers : Each outpost has a radio transceiver. Two outposts can communicate via radio if the distance between them does not exceed $ D $, where $ D $ depends on the transceiver power. All transceivers must have the same $ D $. 2. Satellite Channels : Some outposts have satellite channels. Any two outposts with satellite channels can communicate directly via satellite, regardless of distance. Your task is to determine the minimum $ D $ required such that every pair of outposts has at least one communication path (direct or indirect). 输入格式 First line : $ N $ (number of test cases, $ N \geq 1 $). Per test case : First line : $ S $ (number of satellite channels, $ 1 \leq S \leq 100 $) and $ P $ (number of outposts, $ S < P \leq 500 $). Next $ P $ lines : Coordinates $ (x, y) $ of each outpost (integers between 0 and 10,000). 输出格式 For each test case, output the minimum $ D $ required, rounded to 2 decimal places . 输入样例 1 2 4 0 100 0 300 0 600 150 750 输出样例 212.13