max-points-on-a-line——穷举

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

找出二维平面上处于同一条直线上的最大点数

PS： map用法。for(auto pair:slopes）pair.second

 /**
  * 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:
     int maxPoints(vector<Point> &points) {
         int len = points.size();
         map<float,int> slopes;
         int res=;
         for(int i=;i<len;i++){
             slopes.clear();
             int duplicate=;
             for(int j=i+;j<len;j++){
                 if(points[i].x==points[j].x&&points[i].y==points[j].y){
                     duplicate++;
                 }
                 else{
                     float temp= points[i].x==points[j].x? INT_MAX :(float)(points[i].y-points[j].y)/(points[i].x-points[j].x);
                     slopes[temp]++;
                 }

             }
             res=max(res,duplicate);
             for(auto pair:slopes){
                 res=max(res,pair.second+duplicate);
             }
         }
         return res;
     }
 };