题解 | #多少个点位于同一直线#

/**
 * struct Point {
 *	int x;
 *	int y;
 * };
 */
class Solution {
public:
    /**
     * 
     * @param points Point类vector 
     * @return int整型
     */
    int gcb(int a,int b){
        return b == 0 ? a : gcb(b, a % b);
    }
    int maxPoints(vector<Point>& points) {
        int len = points.size();
        if(len < 2) return len;
        int res = 0;
        for(int i = 0;i < len;i++){
            map<pair<int,int>,int> recordMap;
            int dup = 1;
            for(int j = i + 1;j < len;j++){
                int delta_x = points[i].x - points[j].x;
                int delta_y = points[i].y - points[j].y;
                if(delta_x == 0 && delta_y == 0){
                    dup++;
                }else{
                    int g = gcb(delta_x,delta_y);
                    delta_x = delta_x / g;
                    delta_y = delta_y / g;
                    recordMap[{delta_x,delta_y}]++;
                }
            }
            res = max(res,dup);
            for(auto it=recordMap.begin();it != recordMap.end();it++){
                res = max(res,dup + it->second);
            }
        }
        return res;
    }
   
};