[LintCode] 最多有多少个点在一条直线上

 /**
  * Definition for a point.
  * struct Point {
  *     int x;
  *     int y;
  *     Point() : x(0), y(0) {}
  *     Point(int a, int b) : x(a), y(b) {}
  * };
  */
 class Solution {
 public:
     /**
      * @param points an array of point
      * @return an integer
      */
     int maxPoints(vector<Point>& points) {
         // Write your code here
         unordered_map<float, int> slopes;
         int maxp = , n = points.size();
         for (int i = ; i < n; i++) {
             slopes.clear();
             int duplicate = ;
             for (int j = i + ; j < n; j++) {
                 if (points[i].x == points[j].x && points[i].y == points[j].y) {
                     duplicate++;
                     continue;
                 }
                 float slope = (points[i].x == points[j].x) ? INT_MAX:
                               (float)(points[i].y - points[j].y) / (points[i].x - points[j].x);
                 slopes[slope]++;
             }
             maxp = max(maxp, duplicate);
             for (auto slope : slopes)
                 if (slope.second + duplicate > maxp)
                     maxp = slope.second + duplicate;
         }
         return maxp;
     }
 };