C++ Program to find Permutations in which n people can occupy r seats in a classroom

November 12, 2021

Program to find Permutations in which n people can occupy r seats in a classroom

This is a problem specific program which deals with problems like in how many ways employees can be arranged in the seats available in a company or the same for the students in a school or college.

This problem can be easily solved by the use of the simple formula of permutations which is

nPr =    n! / (n-r)!

Example: we have 5 students and the total number of seats are 6.

Permutations             =    6P5=    6! / (6-5)!   =    720.

So, there are 720 ways in which 5 students can be arranged in 6 seats.

Permutation
Competitive Coding Techniques

Algorithm:-

  1. User gives two inputs(number of people and seats).
  2. The inputs are stored in two int type variables say n(number of people) & r(number of seats).
  3. If the number is people are more than the number of seats then stop the program otherwise go to next step

                  if(r<n)

                     cout<<“Cannot adjust “<<n<<” people on “<<r<<” seats”;

                 return 0;

       4. Find all the possible arrangements using the formula of permutation

               int p=fact(r)/fact(r-n);

       5. Print the output. 

Permutations in which n people can occupy r seats in a class room

C++ Code:-

   //C++ Program

    //Permutations in which n people can occupy r seats

    #include

    using namespace std;

    //function for factorial

    int factorial(int num)

    {

        int fact=1;

        for(int i=num;i>=1;i--)

            fact*=i;

        return fact;

    }

    //main program

    int main()

    {

        int n,r;

        cout<<"Enter number of people: ";

        //user input

        cin>>n;

        cout<<"Enter number of seats: ";

        //user input

        cin>>r;

        //if there are more people than seats

        if(r<n)

        {

            cout<<"Cannot adjust "<<n<<" people on "<<r<<" seats";

            return 0;

        }

        //finding all possible arrangements of n people on r seats

        // by using formula of permutation

        int p = factorial(r)/factorial(r-n);

        //printing output

        cout<<"Total arrangements: "<<p;

        return 0;

    }

Output

    Enter number of people: 5

    Enter number of seats: 6

    Total arrangements: 720
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