【LeetCode】Max Points on a Line

遍历。每次处理两个点，然后找与他们在一条直线上的点，统计并更新，即可。

/**
 * 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) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(points.size()<3) return points.size();
        int count=0;
        int max=0;

        for(int i=0;i<points.size()-1;i++)
        {
            for(int j=i+1;j<points.size();j++)
            {
                int sign=0;
                int a,b,c;
                if(points[i].x==points[j].x) sign=1;
                else
                {
                    a=points[j].x-points[i].x;
                    b=points[j].y-points[i].y;
                    c=a*points[i].y-b*points[i].x;
                }
                int len=0;
                for(int k=0;k<points.size();k++)
                {
                    if((0==sign&&a*points[k].y==c+b*points[k].x)||(1==sign&&points[k].x==points[j].x)) len++;
                }
                if(len>max) max=len;
            }
        }
        return max;
    }
};