题意:在坐标轴中给出n个岛屿的坐标,以及雷达的扫描距离,要求在y=0线上放尽量少的雷达能够覆盖全部岛屿. 很明显的区间选点问题. 代码: /* * Author: illuz <iilluzen[at]gmail.com> * Blog: http://blog.csdn.net/hcbbt * File: l2911.cpp * Create Date: 2013-09-09 20:51:05 * Descripton: */ #include <cstdio> #include…

Assume the coasting is an infinite straight line. Land is in one side of coasting, sea in the other. Each small island is a point locating in the sea side. And any radar installation, locating on the coasting, can only cover d distance, so an island…

解题思路:给出n个岛屿,n个岛屿的坐标分别为(a1,b1),(a2,b2)-----(an,bn),雷达的覆盖半径为r 求所有的岛屿都被覆盖所需要的最少的雷达数目. 首先将岛屿坐标进行处理,因为雷达的位置在x轴上,所以我们设雷达的坐标为(x,0),对于任意一个岛屿p(a,b),因为岛屿要满足在雷达的覆盖范围内,所以 (x-a)^2+b^2=r^2,解得 xmin=a-sqrt(r*r-b*b);//即为区间的左端点 xmax=a+sqrt(r*r-b*b);//即为区间的右端点 接下来区间选点即…

Radar Installation Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 20000/10000K (Java/Other) Total Submission(s) : 22   Accepted Submission(s) : 9 Problem Description Assume the coasting is an infinite straight line. Land is in one side of coa…

题目链接: http://poj.org/problem?id=1328 题意: 在x轴上有若干雷达,可以覆盖距离d以内的岛屿. 给定岛屿坐标,问至少需要多少个雷达才能将岛屿全部包含. 分析: 对于每个岛屿,计算出可以包含他的雷达所在的区间,找到能包含最多岛屿的区间即可. 可以看出这是一个典型的区间问题,我们有几种备选方法: (1)优先选取右端点最大的区间. (2)优先选取长度最长的区间. (3)优先选取与其他区间重叠最少的区间. 2.3很容易想到反例,而1则是正确的,端点越靠右,剩下的区间就越…

Input The input consists of several test cases. The first line of each case contains two integers n (1<=n<=1000) and d, where n is the number of islands in the sea and d is the distance of coverage of the radar installation. This is followed by n li…

Radar Installation Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 54798   Accepted: 12352 Description Assume the coasting is an infinite straight line. Land is in one side of coasting, sea in the other. Each small island is a point loca…

Radar Installation Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 54593   Accepted: 12292 Description Assume the coasting is an infinite straight line. Land is in one side of coasting, sea in the other. Each small island is a point loca…

Radar Installation Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 68578   Accepted: 15368 Description Assume the coasting is an infinite straight line. Land is in one side of coasting, sea in the other. Each small island is a point loca…

Radar Installation Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 106491   Accepted: 23648 Description Assume the coasting is an infinite straight line. Land is in one side of coasting, sea in the other. Each small island is a point loc…