Submission #521326

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Source Code Expand

#include <bits/stdc++.h>
#define rep(i, n) for(int (i) = 0; (i) < (int)(n); ++(i))
#define rep1(i, n) for(int (i) = 1; (i) <= (int)(n); ++(i))
#define all(a) (a).begin(),(a).end()
using namespace std;
typedef long long int lli;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<lli> vlli;
typedef vector<vector<int>> vvi;
typedef vector<vector<double>> vvd;

typedef pair<int, int> P;

double area(const P &v1, const P &v2){
  return (double)abs(v1.first * v2.second - v1.second * v2.first) / 2;
}

int main(){
  int xa, ya, xb, yb, xc, yc;
  cin >> xa >> ya >> xb >> yb >> xc >> yc;
  P BA(xb - xa, yb - ya);
  P CA(xc - xa, yc - ya);
  cout << fixed << setprecision(15);
  cout << area(BA, CA) << endl;
  return 0;
}

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