149. Max Points on a Line

Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.

public class Solution {    public  int maxPoints(Point[] points) {        if (points == null || points.length == 0) {            return 0;        }          HashMap<Double, Integer> map=new HashMap<Double, Integer>();        int max = 1;        for(int i = 0 ; i < points.length; i++) {            // shared point changed, map should be cleared and server the new point            map.clear();            // maybe all points contained in the list are same points,and same points' k is             // represented by Integer.MIN_VALUE            map.put((double)Integer.MIN_VALUE, 1);            int dup = 0;            for(int j = i + 1; j < points.length; j++) {                if (points[j].x == points[i].x && points[j].y == points[i].y) {                    dup++;                    continue;                }                // look 0.0+(double)(points[j].y-points[i].y)/(double)(points[j].x-points[i].x)                // because (double)0/-1 is -0.0, so we should use 0.0+-0.0=0.0 to solve 0.0 !=-0.0                // problem                // if the line through two points are parallel to y coordinator, then K(slop) is                 // Integer.MAX_VALUE                double key=points[j].x - points[i].x == 0 ?                     Integer.MAX_VALUE :                    0.0 + (double)(points[j].y - points[i].y) / (double)(points[j].x - points[i].x);                if (map.containsKey(key)) {                    map.put(key, map.get(key) + 1);                } else {                    map.put(key, 2);                }            }            for (int temp: map.values()) {                // duplicate may exist                if (temp + dup > max) {                    max = temp + dup;                }            }        }        return max;    }}