Submission #2470299

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Source Code Expand

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <utility>
#include <cmath>
#include <iomanip>
#include <queue>
#include <map>
#include <set>
#include <random>
#include <sstream>
#include <stack>
#include <deque>

using namespace std;

#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vl;

int main() {
    int N;
    cin >> N;
    vi x(N);
    vi y(N);
    rep(i,N) cin >> x[i] >> y[i];
    int ans = 0;
    for (int i = 0; i < N; i++) {
        for (int j = i + 1; j < N; j++) {
            for (int k = j + 1; k < N; k++) {
                double x1, y1, x2, y2;
                x1 = x[j] - x[i];
                y1 = y[j] - y[i];
                x2 = x[k] - x[i];
                y2 = y[k] - y[i];
                double S = abs(x1 * y2 - y1 * x2) / 2;
                if (ceil(S) == S && S) ans++;
            }
        }
    }

    cout << ans << endl;

    return 0;
}

Submission Info

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