P82952: Rectangles(2)

#include <iostream>
using namespace std;


struct Rectangle {
    int x_esq, x_dre, y_baix, y_dalt;
};

void llegeix(Rectangle& r) {
    cin >> r.x_esq >> r.x_dre >> r.y_baix >> r.y_dalt;
}

int relacio(const Rectangle& r1, const Rectangle& r2) {
    if (r1.x_esq == r2.x_esq && r1.x_dre == r2.x_dre && r1.y_baix == r2.y_baix && r1.y_dalt == r2.y_dalt) return 4;
    if (r2.x_esq <= r1.x_esq && r2.x_dre >= r1.x_dre && r2.y_baix <= r1.y_baix && r2.y_dalt >= r1.y_dalt) return 1;
    if (r1.x_esq <= r2.x_esq && r1.x_dre >= r2.x_dre && r1.y_baix <= r2.y_baix && r1.y_dalt >= r2.y_dalt) return 2;
    if (r1.y_baix >= r2.y_dalt or r2.y_baix >= r1. y_dalt or r1.x_esq >= r2.x_dre or r2.x_esq >= r1.x_dre) return 0;
    else return 3;
}

//Pre: Llegeix indefinides sequncies de n rectangles
//Post: Escriu la interseccio entre aquests n rectangles
int main() {
    int n;
    while (cin >> n && n != 0)  {
        Rectangle r1, r2;
        llegeix(r2);
        --n;
        bool intersec = true;
        while (intersec && n != 0) {
            r1.x_esq = r2.x_esq;
            r1.x_dre = r2.x_dre;
            r1.y_baix = r2.y_baix;
            r1.y_dalt = r2.y_dalt;
            llegeix(r2);
            if (relacio(r1, r2) == 0) intersec = false;
            else if (relacio(r1, r2) == 1) {
                r2.x_esq = r1.x_esq;
                r2.x_dre = r1.x_dre;
                r2.y_dalt = r1.y_dalt;
                r2.y_baix = r1.y_baix;
            }
            else if (relacio(r1, r2) == 3) {
                if (r1.x_esq > r2.x_esq) r2.x_esq = r1.x_esq;
                if (r1.x_dre < r2.x_dre) r2.x_dre = r1.x_dre;
                if (r1.y_baix > r2.y_baix) r2.y_baix = r1.y_baix;
                if (r1.y_dalt < r2.y_dalt) r2.y_dalt = r1.y_dalt;
            }
            //relacio(r1, r2) == 4 || relacio(r1, r2) == 2 es queda igual
            --n;
        }
        if (not intersec) {
          cout << "interseccio buida" << endl;
          while (n != 0) {
            llegeix(r2);
            --n;
          }
        }
        else {
            cout << "punt inferior esquerre = (" << r2.x_esq << ", " << r2.y_baix << ");";
            cout << " punt superior dret = (" << r2.x_dre << ", " << r2.y_dalt << ")" << endl;
        }
    }
}