Leetcode. 直线上最多的点数

给你一个数组 points ，其中 points[i] = [xi, yi] 表示 X-Y 平面上的一个点。求最多有多少个点在同一条直线上。

示例 1：

输入：points = [[1,1],[2,2],[3,3]]
输出：3

示例 2：

输入：points = [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]]
输出：4

Java

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class maxPoints {
    public static int maxPoints(int[][] points){
        int n = points.length;
        if(n<=2) return n;
        int res =2;

        for(int i=0;i
            Map has = new HashMap();
            int x1 = points[i][0];
            int y1=points[i][1];

            for(int j=i+1;j
                double a,b,c=0;
                int x2 = points[j][0];
                int y2=points[j][1];
                if(x1==x2){
                    a = 1;
                    b = 0;

                    c = -x1;
                    if(c ==-0.0) c = c+0.0;
                }
                else if(y1==y2){
                    a=0;
                    b= 1;
                    c=  -y1;
                    if(c ==-0.0) c = c+0.0;
                }
                else {
                    a = 1.0;
                    b = 1.0 * (x1-x2)/(y2-y1);
                    c = 1.0 * (x1*y2-x2*y1)/(y1-y2);
                    if(c ==-0.0) c = c+0.0;
                }
                String flag = String.valueOf(a)+","+String.valueOf(b)+","+String.valueOf(c);
                System.out.println(flag);
                if(has.containsKey(flag)){
                    int num = has.get(flag) + 1;
                    has.replace(flag, num);
                    res = Math.max(num,res);
                }
                else{
                    has.put(flag, 2);
                }

            }
        }
        return res;
    }
    public static void main(String[] args) {
//        int[][] points = {{1,1},{3,2},{5,3},{4,1},{2,3},{1,4}};
        int[][] points = {{0,0},{2,2},{-1,-1}};
        int res = maxPoints(points);
        System.out.println(res);
    }
}

Python

def maxPoints( points: List[List[int]])->int:
    n = len(points) #  统计点的个数
    if(n<=2):
        return n
    res = 2
    for i in range(n):
        x1,y1 = points[i][0],points[i][1]
        has = {}
        for j in range(i+1,n):
            x2,y2 = points[j][0],points[j][1]
            if x1==x2:
                a,b,c = 1,0,-x1
            elif y1==y2:
                a,b,c = 0,1,-y1
            else:
                a = 1.0
                b = 1.0 * (x1-x2)/(y2-y1)
                c = 1.0 * (x1*y2-x2*y1)/(y1-y2)
            if (a,b,c) in has.keys():
                has[(a,b,c)] +=1
                res = max(res,has[(a,b,c)])
            else:
                has[(a,b,c)] = 2
    return res

if __name__=="__main__":
    points = [[1, 1], [3, 2], [5, 3], [4, 1], [2, 3], [1, 4]]
    res = maxPoints(points)
    print(res)