# 「HDU3622」 Bomb Game 题解

## 题目

### Problem Description

Robbie is playing an interesting computer game. The game field is an unbounded 2-dimensional region. There are N rounds in the game. At each round, the computer will give Robbie two places, and Robbie should choose one of them to put a bomb. The explosion area of the bomb is a circle whose center is just the chosen place. Robbie can control the power of the bomb, that is, he can control the radius of each circle. A strange requirement is that there should be no common area for any two circles. The final score is the minimum radius of all the N circles.

Robbie has cracked the game, and he has known all the candidate places of each round before the game starts. Now he wants to know the maximum score he can get with the optimal strategy.

### Input

The first line of each test case is an integer N (2 <= N <= 100), indicating the number of rounds. Then N lines follow. The i-th line contains four integers x1i, y1i, x2i, y2i, indicating that the coordinates of the two candidate places of the i-th round are (x1i, y1i) and (x2i, y2i). All the coordinates are in the range [-10000, 10000].

### Output

Output one float number for each test case, indicating the best possible score. The result should be rounded to two decimal places.

## 题目大意

$2 \leq N \leq 100$ $-10000 \leq x, y \leq 10000$

## 解题

• 对于每组的两个炸弹：每个炸弹分别从自身的 false 点连向另一个炸弹 true 点，从自身的 true 点连向另一个炸弹的 true

• 对于组外的两个炸弹：如果这两个炸弹的距离小于等于二倍半径，则分别从两个炸弹的 true 点连向另一个炸弹的 false