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NYOJ 287 Radar 两种AC算法实现

第一种方法为自己写的，第二种方法为和队友讨论后改进。

附一句话：博客园是一个分享程序员知识的地方，我不明白，写的代码为啥就不算这个分享的知识呢，为什么老是移除什么首页，不符合规定，所谓云云。。

代码是程序员分享的一切的思想以及细节的终极体现形式。。。

如果有一个博客，都是代码，我反而高兴，终于那些繁琐的，具有二义性、甚至多义性的歧义的文字终于没有了，只剩下了简明、逻辑、有效的东西。。。

本来应该用c++写的，直接使用java写了，感觉更顺手。

Radar

时间限制：1000 ms  |  内存限制：65535 KB
难度：3
 
描述
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 in the sea can be covered by a radius installation, if the distance between them is at most d. 

We use Cartesian coordinate system, defining the coasting is the x-axis. The sea side is above x-axis, and the land side below. Given the position of each island in the sea, and given the distance of the coverage of the radar installation, your task is to write a program to find the minimal number of radar installations to cover all the islands. Note that the position of an island is represented by its x-y coordinates.

 

 
输入
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 lines each containing two integers representing the coordinate of the position of each island. Then a blank line follows to separate the cases. 

The input is terminated by a line containing pair of zeros
输出
For each test case output one line consisting of the test case number followed by the minimal number of radar installations needed. "-1" installation means no solution for that case.
样例输入
3 2
1 2
-3 1
2 1

1 2
0 2

0 0
样例输出
Case 1: 2
Case 2: 1
 1 import java.util.*;
 2 public class Main {
 3   public static void main(String args[]){
 4       Scanner cin=new Scanner(System.in);
 5       int casenum=0;
 6       while(cin.hasNext()){
 7           casenum++;
 8           int n=cin.nextInt();
 9           int d=cin.nextInt();
10           int radarNum=1;
11           
12           if(n==0&&d==0) break;
13           if(d<=0) {System.out.println("Case "+casenum+": -1");}
14  
15 
16           Xy a[]=new Xy[n];
17  
18           boolean slove=true;
19           
20           for(int i=0;i<n;i++){
21     
22               int x=cin.nextInt();
23               int y=cin.nextInt();
24               
25               if(y>d)  slove=false;
26               if(d>0&&slove){
27                a[i]=new Xy();
28              a[i].min=x-Math.sqrt(d*d-y*y);
29              a[i].max=x+Math.sqrt(d*d-y*y);
30           }
31       }
32  
33           if(d>0){
34           if(n==1&&slove) radarNum=1;
35           if(n>1&&slove){
36                 for(int i=0;i<n;i++)
37                     for(int j=i+1;j<n;j++)
38                         if(a[i].min>a[j].min){
39                             Xy tmp=a[i];
40                             a[i]=a[j];
41                             a[j]=tmp;
42                         }
43             double minRadar=a[0].min;
44             double maxRadar=a[0].max;
45             double right=a[0].max;
46                   
47               for(int i=1;i<n;i++){
48  
49                  if(a[i].max<right){
50                      right=a[i].max;
51                  }else
52                      if(right<a[i].min){
53                          right=a[i].max;
54                          radarNum++;
55                      }
56                   
57                   
58               }
59           }
60           System.out.println("Case "+casenum+": "+radarNum);
61           
62       }
63       }
64   }
65 
66   
67 }
68 
69  class Xy {
70  
71               double min=0;
72               double max=0;
73               public Xy(){
74                   
75               }
76               public Xy(int min,int max){
77                   this.min=min;
78                   this.max=max;
79               }
80      
81 }

 

第二种AC方法：

 1 import java.util.*;
 2 public class Main {
 3   public static void main(String args[]){
 4       Scanner cin=new Scanner(System.in);
 5       int casenum=0;
 6       while(cin.hasNext()){
 7           casenum++;
 8           int n=cin.nextInt();
 9           int d=cin.nextInt();
10           int radarNum=1;
11           
12           if(n==0&&d==0) break;
13           if(d<=0) {System.out.println("Case "+casenum+": -1");}
14  
15 
16           Xy a[]=new Xy[n];
17  
18           boolean slove=true;
19           
20           for(int i=0;i<n;i++){
21     
22               int x=cin.nextInt();
23               int y=cin.nextInt();
24               
25               if(y>d)  slove=false;
26               if(d>0&&slove){
27                a[i]=new Xy();
28              a[i].min=x-Math.sqrt(d*d-y*y);
29              a[i].max=x+Math.sqrt(d*d-y*y);
30           }
31       }
32  
33           if(d>0){
34           if(n==1&&slove) radarNum=1;
35           if(n>1&&slove){
36                 for(int i=0;i<n;i++)
37                     for(int j=i+1;j<n;j++)
38                         if(a[i].min>a[j].min){
39                             Xy tmp=a[i];
40                             a[i]=a[j];
41                             a[j]=tmp;
42                         }
43             double minRadar=a[0].min;
44             double maxRadar=a[0].max;
45 
46                   
47               for(int i=1;i<n;i++){
48                  if(a[i].min>maxRadar) {
49                      radarNum++;                     
50                      minRadar=a[i].min;
51                      maxRadar=a[i].max;
52                  }else{
53                      if(a[i].max>maxRadar) 
54                          minRadar=a[i].min;
55                      else{
56                          minRadar=a[i].min;
57                          maxRadar=a[i].max;
58                      }
59                  }
60                    
61                   
62               }
63           }
64           System.out.println("Case "+casenum+": "+radarNum);
65           
66       }
67       }
68   }
69 
70   
71 }
72 
73  class Xy {
74  
75               double min=0;
76               double max=0;
77               public Xy(){
78                   
79               }
80               public Xy(int min,int max){
81                   this.min=min;
82                   this.max=max;
83               }
84      
85 }
posted @ 2012-05-05 19:04  草莓在努力  阅读(1720)  评论(0)  编辑  收藏  举报