Intervals 3

Write a program that, given two intervals, tells if one is inside the other, and computes the interval corresponding to their intersection, or tells that it is empty.

Input : Input consists of four integer numbers a1, b1, a2, b2 that represent the intervals [a1,b1] and [a2,b2]. Assume a1≤ b1 and a2≤ b2.

Output : Print ‘=’ if the intervals are equal, ‘1’ if the first is inside the second (but they are not equal), ‘2’ if the second is inside the first (but they are not equal), or ‘?’ otherwise. Also, print “[]” if the intersection is empty, or “[x,y]” if this is their non-empty intersection.

#include <iostream>
using namespace std;

int main () {
    int a, b, c, d;
    cin >> a >> b >> c >> d;
    
   // Print ‘=’ if the intervals are equal, 
   //‘1’ if the first is inside the second (but they are not equal), 
   //‘2’ if the second is inside the first (but they are not equal), 
    // or ‘?’ otherwise.
    
    if (a == c and b == d) cout << "= , "<< "[" << a << "," << b << "]" << endl;
    else {
        
        if ((a >= c and b < d) or (a > c and b <= d)) cout << "1 , "<< "[" << a << "," << b << "]" << endl;
        
        else {
            
            if ((a <= c and b > d) or (a < c and b >= d)) cout << "2 , "<< "[" << c << "," << d << "]" << endl;
            
            else {
                if (a == d) cout << "? , "<< "[" << a << "," << d << "]" << endl;
                else {
                    
                    if (b == c) cout << "? , "<< "[" << b << "," << c << "]" << endl;
                    
                    else {
                        
                        if (c>=a and c<=b and d>=b)  cout << '?' << ' ' << ',' << ' ' << '[' << c << ',' << b << ']' << endl;
                        
                        else {
                            
                            if (a>=c and a<=d and d<=b)  cout << '?' << ' ' << ',' << ' ' << '[' << a << ',' << d << ']' << endl;
                            
                            else {
                                
                                if (d>=a and d<=b and c<=a)  cout << '?' << ' ' << ',' << ' ' << '[' << a << ',' << d << ']' << endl;
                                
                                else  cout << "? , "<< "[]" << endl;
                            }
                        }
                    }
                }
            }
        }
    }
}