编程之美－－区间重合判断

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

public class SectionCoincide {

    static class Line {
	int x, y;

	public Line(int x, int y) {
	    this.x = x;
	    this.y = y;
	}

	boolean isInclude(Line line) {
	    return x <= line.x && y >= line.y;
	}

	// 排序后使用，前提是 line 在this的右边
	public boolean join(Line line) {
	    if (y < line.x)
		return false;
	    y = line.y;
	    return true;
	}

	public String toString() {
	    return "[" + x + "," + y + "]";
	}
    }

    /**
     * 将其以 x 排序，并合成不相交的 然后用二分查找在这些不相交的 line 中查找看是否有一个能完全覆盖目标
     */
    public static void execute(Line[] lines, Line target) {
	Arrays.sort(lines, new Comparator<Line>() {
	    @Override
	    public int compare(Line o1, Line o2) {
		return o1.x < o1.x ? -1 : (o1.x > o2.x ? 1 : 0);
	    }
	});
	List<Line> list = new ArrayList<Line>();
	list.add(lines[0]);
	int pos = 0;
	for (int i = 1, len = lines.length; i < len; i++) {
	    if (!list.get(pos).join(lines[i])) {
		list.add(lines[i]);
		pos++;
	    }
	}
	// 利用 二分查找在 list 中找出，将target.x,target.y 找出在哪一个区间，看它们是否同一区间
	System.out.println(list + " " + target);
	int a = getIndex(list, target.x);
	int b = getIndex(list, target.y);
	System.out.println(a == b ? "Yes" : "No");

    }

    static int getIndex(List<Line> list, int k) {
	int from = 0, to = list.size() - 1;
	while (from <= to) {
	    int mid = (from + to) >> 1;
	    if (k >= list.get(mid).x && k <= list.get(mid).y)
		return mid;
	    else if (k < list.get(mid).x)
		to = mid - 1;
	    else
		from = mid + 1;
	}
	return -1;
    }

    static final int SIZE = 10;

    public static void main(String args[]) {
	Scanner cin = new Scanner(
		SectionCoincide.class.getResourceAsStream("Line.txt"));

	int g = cin.nextInt();
	while (g-- > 0) {
	    int n = cin.nextInt();
	    Line[] lines = new Line[n];
	    for (int i = 0; i < n; i++) {
		int x = cin.nextInt();
		int y = cin.nextInt();
		lines[i] = new Line(x, y);
	    }
	    int targetx = cin.nextInt();
	    int targety = cin.nextInt();
	    Line target = new Line(targetx, targety);
	    execute(lines, target);
	}
    }
}