[leetcode]max points on a line

 * 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 {
  public int maxPoints(Point[] points){
    if(points.length <= 2) return points.length;

    int result = 0;

    for(int i = 0; i < points.length; i++){
      //key为斜率，value为点数
      HashMap<Double, Integer> map = new HashMap<>();
      //x坐标相等的点的数量
      int samex = 1;
      //记录相同点
      int samep = 0;

      for(int j = 0; j < points.length; j++){
        if(j != i){
          if((points[j].x == points[i].x) && (points[j].y == points[i].y)){
            samep++;
          }

          if(points[j].x == points[i].x){
            samex++;
            continue;
          }
          double k = (double)(points[j].y - points[i].y) / (double)(points[j].x - points[i].x);

          if(map.containsKey(k)){
            map.put(k, map.get(k) + 1);
          }else{
            map.put(k, 2);
          }
          result = Math.max(result, map.get(k) + samep);
        }
      }

      result = Math.max(result, samex);
    }
    return result;
  }
}