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:无需package
3 // 2: 类名必须Main, 不可修改
4 import java.util.Map.Entry;
5
6 public class Demo1 {
7 // 区间树，储存影子的区间
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 }
