LintCode612. K Closest Points

Ladder Only
fb面经题，用PriorityQueue,值得注意的地方是Comparator的写法

/**
 * Definition for a point.
 * class Point {
 *     int x;
 *     int y;
 *     Point() { x = 0; y = 0; }
 *     Point(int a, int b) { x = a; y = b; }
 * }
 */
public class Solution {
    /**
     * @param points a list of points
     * @param origin a point
     * @param k an integer
     * @return the k closest points
     */
    private Point origin;
    public Point[] kClosest(Point[] points, Point origin, int k) {
        // Write your code here
        if (points == null || points.length == 0){
            return points;
        }
        this.origin = origin;
        Point[] results = new Point[k];
        PriorityQueue pq = new PriorityQueue(k, sortByDistance);
        for (Point point : points){
            pq.offer(point);
        }
        for (int i = 0; i < k; i++){
            Point point = pq.poll();
            results[i] = point;
        }
        return results;
    }

    private Comparator sortByDistance = new Comparator(){
        public int compare(Point a, Point b){
            int diff = 0;
            diff = distance(a, origin) - distance(b, origin);
            if (diff == 0){
                diff = a.x - b.x;
            }
            if (diff == 0){
                diff = a.y - b.y;
            }
            return diff;
        }
    };
    
    private int distance(Point a, Point b){
        return (a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y);
    }
        
}