Parallelogram (Editorial)

Written by Zeyneb_Semedli

In this problem we are asked to check whether it is possible to create a parallelogram with the given numbers.

First, 4 numbers are given in the input: a b c and d. If we look at the properties of the parallelogram, we will see that its opposite sides are equal to each other:

     b
   -------
a /      /  c    
  -------
     d

if so, then a=b,c=d.

To solve the problem, let's collect the given numbers in an array.

int n=4;
double a[n];
for(int i=0;i<n;i++)
{
      cin>>a[i];
}

Let's not forget that the numbers given in the input are of "double" type :)

The second step is to stack the array from smallest to largest.That is to sort.

sort(a,a+n)

Let's not forget that we need a new library to implement the sorting function. The name of the library is:

#include <cmath>

And after that, we need to consider the property of the parallelogram in our code.since our numbers are already sorted, we just need to check the equality of the first 2 and last 2 numbers of the array.

After checking the elements of the array, "YES" if it matches our property:

if(a[0]==a[1] && a[2]==a[3])
{
      cout<<"YES";
}

otherwise:

else
{
      cout<<"NO";
}

Let's take a look at our code in general:

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
      int n=4;
      double a[n];
      for(int i=0;i<n;i++)
      {
            cin>>a[i];
      }
      sort(a,a+n);
      if(a[0]==a[1] && a[2]==a[3])
      {
            cout<<"YES";
      }
      else
      {
            cout<<"NO";
      }
}