Question

We have a n*n matrix for example we take n=4 and the matrix is given below.

 1  2  3  4
 5  6  7  8
 9 10 11 12
13 14 15 16

We have to traverse it in the sequence:

1, 2, 3, 4, 8, 12, 16, 15, 14, 13, 9, 5, 6, 7, 11, 10

How can I do this?

Answer 1

“Traversing” in this case probably means accessing and printing each entry.You want to go through it in a clockwise spiral, starting from the top.

Here is an English-sentence-style description of what you need to do:

If you can find a way to go to the TOP-LEFT element of a sub-matrix, read off the entries in the top row left-to-right, read off the entries in the right column top-to-bottom, entries in the bottom row right-to-left, and then the left column bottom-to-top, you have one iteration. You can take the remaining sub-matrix and continue until you have nothing left.

Further hints:

From the cell M[x][y],

• M[x][y+1] is the cell to the RIGHT (so long as y+1<n)
• M[x][y-1] is the cell to the LEFT (so long as y>0)
• M[x+1][y] is the cell BELOW (so long as x+1<n)
• M[x-1][y] is the cell ABOVE (so long as x>0)