算法入门 6.Saruman‘s Army（贪心）

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于 2021-08-22 01:28:14 发布 · 2k 阅读

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#算法

本文介绍了一种策略问题，萨鲁曼如何通过最少的魔晶石（palantirs）确保军队成员都在其有效范围内，每个魔晶石的有效范围为R单位。涉及输入军队位置并计算所需魔晶石数量的算法优化。

Description
Saruman the White must lead his army along a straight path from Isengard to Helm’s Deep. To keep track of his forces, Saruman distributes seeing stones, known as palantirs, among the troops. Each palantir has a maximum effective range of R units, and must be carried by some troop in the army (i.e., palantirs are not allowed to “free float” in mid-air). Help Saruman take control of Middle Earth by determining the minimum number of palantirs needed for Saruman to ensure that each of his minions is within R units of some palantir.
Input
The input test file will contain multiple cases. Each test case begins with a single line containing an integer R, the maximum effective range of all palantirs (where 0 ≤ R ≤ 1000), and an integer n, the number of troops in Saruman’s army (where 1 ≤ n ≤ 1000). The next line contains n integers, indicating the positions x1, …, xn of each troop (where 0 ≤ xi ≤ 1000). The end-of-file is marked by a test case with R = n = −1.
Out