ШВБ_21-22_N3

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int, int>
#define pb(x) push_back(x)
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}

void cvl(vector <ll> &v) {
    for (auto x : v) cout << x << ' ';
    cout << "\n";
}


void cvv(vector <vector <int> > &v) {
    for (auto x : v) cv(x);
    cout << "\n";
}

void cvb(vector <bool> v) {
    for (bool x : v) cout << x << ' ';
    cout << "\n";
}

void cvs(vector <string>  v) {
    for (auto a : v) {
        cout << a << "\n";
    }
}

void cvp(vector <pii> a) {
    for (auto p : a) {
        cout << p.first << ' ' << p.second << "\n";
    }
    cout << "\n";
}

bool sh = 0;

int mx = 2e3 + 100;

vector <vector <bool> > was(mx, vector <bool> (mx, 0));
vector <vector <int> > dsk(mx, vector <int> (mx, 0));

vector <int> dx = {-1, 1, 0, 0}, dy = {0, 0, 1, -1};
bool ok(int i, int j) {
    return i >= 0 && i < mx && j >= 0 && j < mx && dsk[i][j] == 1 && !was[i][j];
}

int cnt = -1;

void dfs(int i, int j) {
    cnt++;
    was[i][j] = 1;
    for (int to = 0; to < 4; ++to) {
        int x = i + dx[to], y = j + dy[to];
        if (ok(x, y)) {
            dfs(x, y);
        }
    }
}


int main() {
    /*ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);*/

    int n; cin >> n;
    for (int i = 0; i < n; ++i) {
        int x1, y1, x2, y2;
        cin >> x1 >> y1 >> x2 >> y2;
        x1 += 1e3;
        x2 += 1e3;
        y1 += 1e3;
        y2 += 1e3;
        if (x1 > x2) {
            swap(x1, x2);
        }
        if (y1 > y2) {
            swap(y1, y2);
        }
        for (int j = x1; j < x2; ++j) {
            for (int i = y1; i < y2; ++i) {
                dsk[i][j] = 1;
            }
        }
    }
    if (sh) {
        cout << "dsk\n";
        for (int i = 1e3 -  10; i < 1e3 + 20; ++i) {
            for (int j = 1e3 - 10; j < 1e3 + 20; ++j) {
                cout << dsk[i][j] << ' ';
            } cout << "\n";
        } cout << "\n";
        //cout << "was\n";
        //cvv(was);
    }
    int ans = -1;
    for (int i = 0; i < mx; ++i) {
        for (int j = 0; j < mx; ++j) {
            if (dsk[i][j] == 1 && !was[i][j]) {
                cnt = 0;
                dfs(i, j);
            }
            ans = max(ans, cnt);
        }
    }
    if (sh) {
        cout << "ans = \n";
    }
    cout << ans;
}
/*
5
-4 -5 -1 -1
-2 -2 2 4
-3 3 7 4
7 1 6 3
7 1 8 -2
*/