In-place convert matrix in specific order - GeeksforGeeks

In-place convert matrix in specific order - GeeksforGeeks
Write a code to convert a matrix in specific way without using extra space.

Input:
      1 2 3
      4 5 6
      7 8 9

Output:
      1 6 7
      2 5 8
      3 4 9

every even column in output matrix has elements of corresponding row in input matrix in opposite order.

void transformMatrix(int *A, int r, int c)

{

    // Invert even rows

    for (int i = 1; i < r; i = i + 2)

        for (int j1 = 0, j2 = c - 1; j1 < j2; j1++, j2--)

            swap(*(A + i*c + j1), *(A + i*c + j2));

 

    // Rest of the code is from below post

    // http://tinyurl.com/j79j445

    int size = r*c - 1;

    int t; // holds element to be replaced, eventually

           // becomes next element to move

    int next; // location of 't' to be moved

    int cycleBegin; // holds start of cycle

 

    bitset<HASH_SIZE> b; // hash to mark moved elements

 

    b.reset();

    b[0] = b[size] = 1;

    int i = 1; // Note that A[0] and A[size-1] won't move

    while (i < size)

    {

        cycleBegin = i;

        t = A[i];

        do

        {

            // Input matrix [r x c]

            // Output matrix 1

            // i_new = (i*r)%(N-1)

            next = (i*r)%size;

            swap(A[next], t);

            b[i] = 1;

            i = next;

 

        }  while (i != cycleBegin);

 

        // Get Next Move (what about querying

        // random location?)

        for (i = 1; i < size && b[i]; i++)

            ;

    }

}

Read full article from In-place convert matrix in specific order - GeeksforGeeks