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=0;
        for(int i=0;i<len;i++){
            slopes.clear();
            int duplicate=1;
            for(int j=i+1;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;
    }
};