LeetCode : 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.

int maxPoints(vector<Point> &points) {int length=points.size();int maxpoints=0;if(length<1) return 0;if(length==1) return 1;double *Slope=new double[length-1];multimap<double ,double> mp;multimap<double ,double> mpTemp;for (int j = 0; j < length; j++){Point p=points[j];double x0=p.x,y0=p.y;double x1=0,y1=0;double k=0;//斜率int equalNum=0;multimap<double,double >::iterator iter;multimap<double,double >::iterator iterTemp;multimap<double,double >::iterator iter1;for (int i = 0; i < length; i++){x1=points[i].x;y1=points[i].y;if((x1-x0)!=0){k=(y1-y0)/(x1-x0);}else if((x1-x0)==0&&(y1-y0)!=0){k=1.79769e+308;}else if((x1-x0)==0&&(y1-y0)==0){equalNum++;continue;}iter=mp.find(k);if(iter==mp.end()){mp.insert(pair<double,double >(k,2));}else{iter->second+=1;}}if(equalNum>1){for(iter=mp.begin();iter!=mp.end();++iter){iter->second+=1;}}for (iterTemp=mp.begin(); iterTemp!=mp.end(); iterTemp++){mpTemp.insert(pair<double,double>(iterTemp->second,iterTemp->first));}iter1=mpTemp.end();if(mpTemp.size()>0){iter1--;if(iter1->first>maxpoints){maxpoints=iter1->first;}}else{maxpoints=equalNum;}mpTemp.clear();mp.clear();}return maxpoints;    }