Submission #5544168

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

typedef pair<int, int> P;
typedef pair<P, int> Pi;
const int N = (int)1e5 + 50;

int r, c;
int n;
vector<Pi> pts;
int in[N];

int on_bound(int x, int y) {
    return x == 0 || x == r || y == 0 || y == c;
}

int bound(int x, int y) {
    if(x == 0 && y == 0) return 0;
    if(x == 0 && 0 < y && y < c) return 1;
    if(x == 0 && y == c) return 2;
    if(0 < x && x < r && y == c) return 3;
    if(x == r && y == c) return 4;
    if(x == r && 0 < y && y < c) return 5;
    if(x == r && y == 0) return 6;
    if(0 < x && x < r && y == 0) return 7;

//    cout << x << " " << y << endl;
    assert(false);
}

bool cmp(P p1, P p2) {
    int b1 = bound(p1.first, p1.second), b2 = bound(p2.first, p2.second);
    if(b1 != b2) return b1 < b2;
    if(b1 == 1) return p1.second < p2.second;
    if(b1 == 3) return p1.first < p2.first;
    if(b1 == 5) return p1.second > p2.second;
    if(b1 == 7) return p1.first > p2.first;
}

int main() {
    cin >> r >> c >> n;
    for(int i = 0; i < n; i++) {
        int x1, y1, x2, y2;
        cin >> x1 >> y1 >> x2 >> y2;
        if(on_bound(x1, y1) && on_bound(x2, y2)) {
            pts.push_back({{x1, y1}, i});
            pts.push_back({{x2, y2}, i});
        }
    }
    sort(pts.begin(), pts.end(), [](const Pi &p1, const Pi &p2) {
        return cmp(p1.first, p2.first);
    });
    stack<int> S;

    for(const auto &p : pts) {
        int cur = p.second;
        if(in[cur]) {
            if(!S.empty() && S.top() == cur) {
                S.pop();
                in[cur] = false;
            }
            else {
                return cout << "NO" << endl, 0;
            }
        } else {
            in[cur] = true;
            S.push(cur);
        }
    }
    return cout << "YES" << endl, 0;

}

Submission Info

Judge Result