算法标签：

模拟

题解：

分别以每个点为基准，计算与其他点的斜率，将斜率排序后统计斜率最多的值。

#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;

const double esp = 1e-10;
int x[800], y[800], N;
double k[800];

int main() {
    while (cin >> N && N) {
        for (int i = 0; i < N; i++) {
            cin >> x[i] >> y[i];
        }
        int ret = 0;
        for (int i = 0; i < N; i++) {
            int cnt = 0, cinf = 0;
            for (int j = 0; j < N; j++) {
                if (j != i) {
                    if (x[j] == x[i]) {
                        cinf++;
                    } else {
                        k[cnt++] = (y[j] - y[i]) * 1.0 / (x[j] - x[i]);
                    }
                }
            }
            sort(k, k + cnt);
            int c = 0;
            ret = max(ret, cinf + 1);
            for (int j = 0; j < cnt; j++) {
                if (!j || fabs(k[j] - k[j - 1]) < esp) {
                    c++;
                } else {
                    ret = max(c + 1, ret);
                    c = 1;
                }
            }
            ret = max(ret, c + 1);
        }
        cout << ret << endl;
    }
    return 0;
}