Pravokutni

input/code.cpp: In function 'int main()':
input/code.cpp:29:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
input/code.cpp:31:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&x[i],&y[i]);
         ~~~~~^~~~~~~~~~~~~~~~~~~~

#pragma GCC optimize("O3")
#pragma GCC target("arch=sandybridge")
#include<bits/stdc++.h>
using namespace std;
struct point {
    int x, y;
    point(int X, int Y) {
        x = X;
        y = Y;
    }
    point() {}
    bool operator==(point b)
    {
        return x == b.x && y == b.y;
    }
    bool operator!=(point b)
    {
        return !(*this == b);
    }
} v[1555], p[1555];
bool operator<(const point &a, const point &b)
{
    return a.x == b.x ? a.y < b.y : a.x < b.x;
}
int x[1555], y[1555];
int main()
{
    int n;
    scanf("%d", &n);
    for (int i = 0; i < n; ++i) {
        scanf("%d%d",&x[i],&y[i]);
    }
    int r = 0;
    for (int it = 0; it < n; ++it) {
        int o = 0;
        for (int j = 0; j < n; ++j) {
            if (it == j) continue;
            point z(x[it] - x[j], y[it] - y[j]);
            int u = abs(__gcd(z.x, z.y));
            z.x /= u;
            z.y /= u;
            p[o++] = z;
        }
        memmove(v, p, (n - 1) * sizeof(point));
        sort(v, v + n - 1);
        for (int i = 0; i < n - 1; ++i) {
            int t = i;
            while (t + 1 < n - 1 && p[t + 1] == p[t]) ++t;
            point z(p[i].y, -p[i].x);
            auto it = equal_range(v,v+n-1, z);
            if (*it.first != z) continue;
            r += (it.second - it.first) * (t - i + 1);
            i = t;
        }
    }
    cout << r << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED