Rearrange Geek and his Classmates.cpp

/*
Geek and his classmates are playing a prank on their Computer Science teacher. 
They change places every time the teacher turns to look at the blackboard. 

Each of the N students in the class can be identified by a unique roll number X and each 
desk has a number i associated with it. Only one student can sit on one desk. 
Each time the teacher turns her back, a student with roll number X sitting on desk number 
i gets up and takes the place of the student with roll number i.

If the current position of N students in the class is given to you in an array, such that 
i is the desk number and a[i] is the roll number of the student sitting on the desk, 
can you modify a[ ] to represent the next position of all the students ? 


Example 1:

Input:
N = 6
a[] = {0, 5, 1, 2, 4, 3}
Output: 0 3 5 1 4 2
Explanation: After reshuffling, the modified 
position of all the students would be 
{0, 3, 5, 1, 4, 2}.
*/


    void prank(long long a[], int n){
        // code here
        for(long long int i=0;i<n;i++)
        {
            long long int x = a[i];
            long long int y = a[x];
            a[i] = x + (y%n)*n;
        }
        for(long long int i=0;i<n;i++)
        {
            a[i]/=n;
        }
    }