Problem 1400. Spiral Matrix

for a given integer n>=3, generate a matrix of nxn such that the value n^2 is at bottom left and its decreasing towards center around the corner forming a spiral.{clockwise spiral- starting from bottom left}

Examples:

 Input  n = 5
 Output y is [ 21 20 19 18 17;
               22 7  6  5  16;
               23 8  1  4  15;
               24 9  2  3  14;
               25 10 11 12 13];

 Input  n = 4
 Output y is [ 13 12 11 10 
               14 3  2  9
               15 4  1  8
               16 5  6  7]