noip模拟赛 三角形

#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;

ll n, cnt, f[300010][4];
double k[300010], b[300010];

int main()
{
    scanf("%lld", &n);
    for (int i = 1; i <= n; i++)
    {
        ll a, b, c;
        scanf("%lld%lld%lld", &a, &b, &c);
        k[i] = (double)(-a) / b;
    }
    sort(k + 1, k + 1 + n);
    for (int i = 1; i <= n; i++)
    {
        if (k[i] != k[i - 1])
            b[++cnt] = 1;
        else
            b[cnt]++;
    }
    f[0][0] = 1;
    for (int i = 1; i <= cnt; i++)
    {
        f[i][0] = 1;
        for (int j = 1; j <= 3; j++)
            f[i][j] = f[i - 1][j] + f[i - 1][j - 1] * b[i];
    }
    printf("%lld\n", f[cnt][3]);

    return 0;
}