Submission #5559340

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Source Code Expand

#include <bits/stdc++.h>
#define rep(i,n) for(int i=(0);i<(n);i++)

using namespace std;

typedef long long ll;

int R, C, N;

struct point{
	int x, y, id;
};

int lev(point p){
	if(p.y == 0) return 0;
	if(p.x == C) return 1;
	if(p.y == R) return 2;
	if(p.x == 0) return 3;
	return 4;
}

bool comp(point lhs, point rhs){
	int levl = lev(lhs);
	int levr = lev(rhs);
	if(levl != levr) return levl < levr;

	if(levl == 0) return lhs.x < rhs.x;
	if(levl == 1) return lhs.y < rhs.y;
	if(levl == 2) return lhs.x > rhs.x;
	if(levl == 3) return lhs.y > rhs.y;
}

int main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);


	cin >> R >> C >> N;

	vector<point> v;
	int id = 0;
	rep(i, N){
		int x1, y1, x2, y2;
		cin >> x1 >> y1 >> x2 >> y2;

		point p1 = (point){x1, y1, id};
		point p2 = (point){x2, y2, id};
		if(lev(p1) < 4 && lev(p2) < 4){
			v.push_back(p1);
			v.push_back(p2);
			id++;
		}
	}

	if(v.size() == 0){
		cout << "YES" << endl;
		return 0;
	}

	sort(v.begin(), v.end(), comp);

	stack<int> stc;
	set<int> st;

	for(int i = 0; i < v.size(); i++){
		point p = v[i];
		if(stc.size() == 0){
			stc.push(p.id);
			st.insert(p.id);
			continue;
		}

		if(stc.top() == p.id){
			stc.pop();
			st.erase(p.id);
			continue;
		}

		auto itr = st.find(p.id);
		if(itr == st.end()){
			stc.push(p.id);
			st.insert(p.id);
		}else{
			cout << "NO" << endl;
			return 0;
		}
	}

	cout << "YES" << endl;
}

Submission Info

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