poj3668

简单题

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
using namespace std;

const int maxn =205;

struct Point
{
    int x, y;
}slope[maxn * maxn], point[maxn];

int n, tot;

bool operator == (const Point &a, const Point &b)
{
    return a.x == b.x && a.y == b.y;
}

bool operator < (const Point &a, const Point &b)
{
    if (a.x == b.x)
        return a.y < b.y;
    return a.x < b.x;
}

void input()
{
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
        scanf("%d %d", &point[i].x, &point[i].y);
}

int gcd(int a, int b)
{
    b = b % a;
    while (b)
    {
        a = a % b;
        swap(a, b);
    }
    return a;
}

void simplify(int &x, int &y)
{
    if (x == 0)
    {
        y = 1;
        return;
    }
    if (y == 0)
    {
        x = 1;
        return;
    }
    if (y < 0)
    {
        x = -x;
        y = -y;
    }
    int g = gcd(x < 0 ? -x : x, y);
    x /= g;
    y /= g;
}

void work()
{
    tot = 0;
    for (int i = 0; i < n - 1; i++)
        for (int j = i + 1; j < n; j++)
        {
            slope[tot].x = point[j].x - point[i].x;
            slope[tot].y = point[j].y - point[i].y;
            simplify(slope[tot].x, slope[tot].y);
//            printf("%d %d\n", slope[tot].x, slope[tot].y);
            tot++;
        }
}

int main()
{
//    freopen("t.txt", "r", stdin);
    input();
    work();
    sort(slope, slope + tot);
    tot = unique(slope, slope + tot) - slope;
    printf("%d\n", tot);
    return 0;
}