Submission #1187582

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Source Code Expand

#include <cstdio>
#include <cmath>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <map>
#include <set>
#include <array>
#include <queue>
#include <string>
#include <vector>
#include <numeric>
#include <algorithm>
#include <functional>
#define MOD 1000000007
#define INF 11234567890
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;
typedef std::pair<int, int> P;

int Ax, Ay, Bx, By, N, X[112], Y[112];
LL ans;

bool IsIntersected(int ax,int ay,int bx, int by, int cx, int cy, int dx, int dy)
{
	auto tc = (ax - bx)*(cy - ay) + (ay - by)*(ax - cx);
	auto td = (ax - bx)*(dy - ay) + (ay - by)*(ax - dx);
	if (tc*td < 0) { return true; }
	return false;
}

int main()
{
	in >> Ax >> Ay >> Bx >> By >> N;
	rep(i, N) { in >> X[i] >> Y[i]; }

	LL hit = 0;
	rep(i, N)
	{
		if (IsIntersected(X[i], Y[i], X[(i + 1) % N], Y[(i + 1) % N], Ax, Ay, Bx, By) == true)
		{
			++hit;
		}
	}
	ans = hit / 2 + 1;

	out << ans << std::endl;
	return 0;
}

Submission Info

Judge Result