太陽（藍橋杯14屆）

小菜碟子發表於2024-04-11

https://www.lanqiao.cn/problems/3529/learning/?subject_code=2&group_code=5&match_num=14&match_flow=1&origin=cup

 1 import java.util.*;
 2 // 1:無需package
 3 // 2: 類名必須Main, 不可修改
 4 import java.util.Map.Entry;
 5 
 6 public class Demo1 {
 7     // 區間樹，儲存影子的區間
 8     static TreeMap<Double, Double> m = new TreeMap<>();
 9 
10     public static void main(String[] args){
11         Scanner sc=new Scanner(System.in);
12         
13         int n=sc.nextInt();
14         double x=sc.nextDouble();
15         double y=sc.nextDouble();
16         
17         List<Line> lines=new ArrayList<>();
18         
19         for (int i = 0; i < n; i++) {
20             double left=sc.nextDouble();
21             double height=sc.nextDouble();
22             double length=sc.nextDouble();
23             
24             lines.add(new Line(left, height, length));
25         }
26         
27         lines.sort((l1,l2)->Double.compare(l2.y, l1.y));
28         
29         long res=0;
30         
31         for(Line o:lines) {
32             double l=GetTouYing(o.leftx,o.y,x,y);
33             double r=GetTouYing(o.rightx, o.y, x, y);
34             if(!QuaryCover(l,r)) res++;
35             AddRange(l,r);
36         }
37         
38         sc.close();
39         System.out.print(res);
40     }
41     
42     public static void AddRange(double l,double r) {
43         Entry<Double,Double> L=m.floorEntry(l);
44         Entry<Double,Double> R=m.floorEntry(r);
45         
46         if(L != null && L.getValue()>=l) l=L.getKey();
47         if(R != null && R.getValue()>=r) r=R.getValue();
48         
49         m.subMap(l, r).clear();
50         m.put(l, r);
51     }
52     
53     public static boolean QuaryCover(double l,double r) {
54         Entry<Double,Double> L=m.floorEntry(l);
55         return L != null && L.getValue()>=r;
56     }
57     
58     public static double GetTouYing(double x1,double y1,double x2,double y2) {
59         return x1 - y1 * (x1 - x2) / (y1 - y2);
60     }
61     
62     public static class Line {
63         double leftx;
64         double rightx;
65         double y;
66         double length;
67         
68         Line(double left,double height,double length){
69             this.leftx=left;
70             this.y=height;
71             this.length=length;
72             this.rightx=left+length;
73         }
74     }
75 }

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