已知:
给定我们一个点的集合,找出其中是否存在四个点能构成一个矩形
思路:
这道题的思路,往简单了想,我是这么考虑的:一个矩形的四个点分为左上右上左下右下,我们遍历点集合的所有点,假设当前点是左上,找到满足要求的所有左下和右上,然后左下和右上配对产生右下,判断右下是否在点集合之中,如果存在,则返回“YES”,如果遍历完都不存在,就返回“NO”
/* public class Point { public int x; public int y; public Point(int x, int y) { this.x = x; this.y = y; } } */ public class Solution { /** * @param pointSet: The point set * @return: The answer */ public String rectangle(Point[] pointSet) { for (Point p : pointSet) { if (calculate(p, pointSet)) { return "YES"; } } return "NO"; } private boolean calculate(Point p, Point[] pointSet) { for (int i = 0; i < pointSet.length; i++) { if (pointSet[i].x == p.x && pointSet[i].y < p.y) { for (int j = 0; j < pointSet.length; j++) { if (pointSet[j].x > p.x && pointSet[j].y == p.y) { Point temp = new Point(pointSet[j].x, pointSet[i].y); if (contain(pointSet, temp)) { return true; } } } } } return false; } private boolean contain(Point[] pointSet, Point temp) { for (Point p : pointSet) { if (p.x == temp.x && p.y == temp.y) { return true; } } return false; } }