编程题一道

2017.04.26

摸金校尉通过激光防范到达指定位置：

package stackAndQueue;


import java.util.Scanner;

class Point{
	int x;
	int y;
	Point(int x, int y){
		this.x = x;
		this.y = y;
	}
}

class Line{
	Point start;
	Point end;
	Line(Point start, Point end){
		this.start = start;
		this.end = end;
	}
}

public class Main {
	

	
	public static void main(String[] args) {
		//读取目标行列数
		Scanner sc = new Scanner(System.in);
		int m,n;
		int count = 0;
		m = sc.nextInt();
		n = sc.nextInt();
		
		//读取激光数据
		Scanner sc1 = new Scanner(System.in);
		String info = sc1.nextLine();

		String[] points_pos = info.split(" ");
		int[] positions = new int[points_pos.length];
		for(int i=0;i<points_pos.length;i++){
			positions[i] = Integer.parseInt(points_pos[i]);
		}
		count = positions[0];
		int num = 1;
		Line[] lines = new Line[count];
		
		for(int i=0;i<count;i++){
			Point start = new Point(positions[num++],positions[num++]);
			Point end = new Point(positions[num++],positions[num++]);
			Line line = new Line(start, end);
			lines[i] = line;
		}
		//如果连接交叉线段，记录上下左右四个方位的最大值，如果上下到顶或者左右到顶即不可到达
		for(int i=0;i<lines.length;i++){
			int max_x = lines[i].start.x>lines[i].end.x?lines[i].start.x:lines[i].end.x;
			int min_x = lines[i].start.x<lines[i].end.x?lines[i].start.x:lines[i].end.x;
			int max_y = lines[i].start.y>lines[i].end.y?lines[i].start.y:lines[i].end.y;
			int min_y = lines[i].start.y<lines[i].end.y?lines[i].start.y:lines[i].end.y;;
			Line line1 = lines[i];
			for(int j=0;j<lines.length;j++){
				Line line2 = lines[j];
				boolean flag = false;
				int d = (line1.end.x - line1.start.x)*(line2.end.y-line2.start.y)-(
						line1.end.y-line1.start.y)*(line2.end.x-line2.start.x);
				if(d!=0){
					double r = (line1.start.y-line2.start.y)*(line2.end.x-line2.start.x)-(
							line1.start.x-line2.start.x)*(line2.end.y-line2.start.y)/(double)d;
					double s = (line1.start.y-line2.start.y)*(line1.end.x-line1.start.x)-(
							line1.start.x-line2.start.x)*(line1.end.y-line1.start.y)/(double)d;
					if(r>=0 && r<=1 && s>=0 && s<=1){
						flag = true;
					}
				}
				//线段相交，进行极值更新
				if(flag==true){
					int max_x1 = lines[j].start.x>lines[j].end.x?lines[j].start.x:lines[j].end.x;
					int min_x1 = lines[j].start.x<lines[j].end.x?lines[j].start.x:lines[j].end.x;
					int max_y1 = lines[j].start.y>lines[j].end.y?lines[j].start.y:lines[j].end.y;
					int min_y1 = lines[j].start.y<lines[j].end.y?lines[j].start.y:lines[j].end.y;
					max_x = max_x>max_x1?max_x:max_x1;
					min_x = min_x<min_x1?min_x:min_x1;
					max_y = max_y>max_y1?max_y:max_y1;
					min_y = min_y<min_y1?min_y:min_y1;
					if(max_x>m || min_x<0 || min_y<0 || max_y>n)
					{
						System.out.println('0');
						return;
					}
				}
			}
		}
		System.out.println('1');	
	}

}