poj2780 简单几何（同一条直线上最多由几个点）

 /*
Time:2019.11.15
Author: Goven
type：简单几何（同一条直线上最多由几个点） 
err:
ref:
*/
#include<iostream>

using namespace std;

int x[1005], y[1005];

int main()
{
    int n;
    while (cin >> n) {
        for (int i = 0 ; i < n; i++) {
            cin >> x[i] >> y[i];
        } 
        int x1, y1, cnt, max_c = 0;
        for (int i = 0; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                cnt = 2;
                y1 = y[j] - y[i];
                x1 = x[j] - x[i];
                for (int k = j + 1; k < n; k++) {
                    if (y1 * (x[k] - x[i]) == x1 * (y[k] - y[i])) cnt++;
                }
                max_c = max(max_c, cnt);
            }
        }
        cout << max_c << endl;
    }
    
    return 0;
}