蓝桥杯-平面切分

本题主要要去除重复的直线和直线交点，然后切成的平面数量为1+不同直线数量+不同交点数量

但是注意java要重写equals()与hashCode()方法,因为java是用地址来判断所以要重写

idea重写快捷键 Alt+Insert

eclipse重写快捷键 Alt+shift+s 然后加h

equals()方法的重写

Java篇 - hashCode和equals姐妹花

import java.util.*;


public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        int[][] a = new int[n][2];
        for (int i = 0; i < n; i++) {
            a[i][0] = sc.nextInt();
            a[i][1] = sc.nextInt();
            for(int j=0;j set = new HashSet<>();
            for (int j = 0; j < i; j++) {
                if (a[i][0] == a[j][0]){
                    continue;
                }
                double x = (a[i][1] - a[j][1])*1.0 / (a[j][0] - a[i][0]) + 0.0;
                double y = a[i][0] * x + a[i][1] + 0.0;
                Point p = new Point(x, y);
                if (!set.contains(p)) {
                    set.add(p);
                    c++;
                }
            }
            count+=c;
        }

        System.out.println(count);
        sc.close();
    }


}
/**
 * @author forward
 *
 */
class Point {
    private double x;
    private double y;

    public Point(Double x, Double y) {
        this.x = x;
        this.y = y;
    }

    @Override
    public int hashCode() {
        return Objects.hash(x, y);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Point other = (Point) obj;
        return Double.doubleToLongBits(x) == Double.doubleToLongBits(other.x)
                && Double.doubleToLongBits(y) == Double.doubleToLongBits(other.y);
    }

    


    
//    @Override
//    public boolean equals(Object o) {
//        if (this == o) return true;
//        if (o == null || getClass() != o.getClass()) return false;
//        Point point = (Point) o;
//        return Double.compare(point.x, x) == 0 && Double.compare(point.y, y) == 0;
//    }
//
//    @Override
//    public int hashCode() {
//        return Objects.hash(x, y);
//    }
    //    @Override
//    public boolean equals(Object o) {
//        if (this == o) return true;
//        if (o == null || getClass() != o.getClass()) return false;
//        Point point = (Point) o;
//        return x == point.x &&
//                y == point.y;
//    }
//
//    @Override
//    public int hashCode() {
//        return Objects.hash(x, y);
//    }
}

C++代码

#include
#include
#include
#include
#include
#include