poj算法题1018——Communication System

最新推荐文章于 2018-08-11 10:37:53 发布

YxuanChen

最新推荐文章于 2018-08-11 10:37:53 发布

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分类专栏： poj算法题文章标签：算法 poj

本文链接：https://blog.youkuaiyun.com/qq_30964897/article/details/53439041

本文介绍了如何解决poj算法题1018，该题目涉及通信系统的设备选择，目标是最大化整体带宽与价格的比例。解题策略包括设备带宽排序、枚举法和动态规划。尽管最终采用了较为直观的方法，但通过剪枝减少了计算量，最终实现的C++代码已通过测试。

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Communication System

Description

We have received an order from Pizoor Communications Inc. for a special communication system. The system consists of several devices. For each device, we are free to choose from several manufacturers. Same devices from two manufacturers differ in their maximum bandwidths and prices.
By overall bandwidth (B) we mean the minimum of the bandwidths of the chosen devices in the communication system and the total price (P) is the sum of the prices of all chosen devices. Our goal is to choose a manufacturer for each device to maximize B/P.

Input

The first line of the input file contains a single integer t (1 ≤ t ≤ 10), the number of test cases, followed by the input data for each test case. Each test case starts with a line containing a single integer n (1 ≤ n ≤ 100), the number of devices in the communication system, followed by n lines in the following format: the i-th line (1 ≤ i ≤ n) starts with mi (1 ≤ mi ≤ 100), the number of manufacturers for the i-th device, followed by mi pairs of positive integers in the same line, each indicating the bandwidth and the price of the device respectively, corresponding to a manufacturer.

Output

Your program should produce a single line for each test case containing a single number which is the maximum possible B/P for the test case. Round the numbers in the output to 3 digits after decimal point.

Sample Input

1 3
3 100 25 150 35 80 25
2 120 80 155 40
2 100 100 120 110

Sample Output

0.649

在这里我把输入输出说一下吧，写程序的时候没看清楚被这个坑死了= =：
输入：
第一行第一个数字时进行测试的用例个数t（1<=t<=10），第二个数字是该测试用例所需设备的个数n（1<=n<=100），该用例接下来几行第一个数字都是每个设备所有的供应商数量i（1<=i<=n）,之后的数据是各个供应商的带宽和价格。
输出：
将所有用例的最大b/p打印出来，一行输出一个。

接下