RQNOJ 150轰炸(求最多有几个点共线)

/*

*  题意：求最多有多少个点共线 

*  思路：枚举两点求直线，枚举有多少个点在直线上 

*/



#include <cstdio>

#include <iostream>



using namespace std;



const int N = 705;



struct point {

	int x;

	int y;

}p[N];



int solve(int n) {

	int a, b, c, counts, ans = -1;

	for (int i=0; i<n; ++i) { 

		for (int j=i+1; j<n; ++j) {

			a = p[j].y - p[i].y;  //一般直线方程系数 

			b = p[i].x - p[j].x;

			c = p[i].y * p[j].x - p[i].x * p[j].y;

			counts = 0;

			for (int k=0; k<n; ++k) {//枚举判断有几个点在直线上 

				if (a*p[k].x+b*p[k].y+c == 0) ++counts;

			}

			if (counts > ans) ans = counts;

		}

	}

	return ans;

}



int main() {

	int n;

	while (scanf("%d", &n) != EOF) {

		for (int i=0; i<n; ++i) scanf("%d%d", &p[i].x, &p[i].y);

		int ans = solve(n);

		printf ("%d\n", ans);

	}

	return 0;

}