Submission #111036

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <numeric>

#define rep(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define ALL(v) (v).begin(), (v).end()
#define REV(s) (s).rbegin(), (s).rend()
#define MP make_pair
#define X first
#define Y second

using namespace std;

static const double EPS = 1e-9;

typedef pair<int, int> P;
typedef long long ll;

template<class T>
inline T sq(T a){return a*a;}

double dist(double x, double y, double xx, double yy){
	return sqrt(sq(x-xx)+sq(y-yy));
}

int main(){
	int x[3], y[3];
	rep(i, 3) cin >> x[i] >> y[i];

	double d[3];
	rep(i, 3) d[i] = dist(x[i], y[i], x[(i+1)%3], y[(i+1)%3]);
	double s = (d[0]+d[1]+d[2])/2;

	cout <<	sqrt(s*(s-d[0])*(s-d[1])*(s-d[2])) << endl;
	
	return 0;
}

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