/// Problem statement: Fill a W X H matrix in spiral fashion outside to inside clockwise
/// For ex: 4 X 6 matrix would look like
///  1       2       3       4
/// 16      17      18       5
/// 15      24      19       6
/// 14      23      20       7
/// 13      22      21       8
/// 12      11      10       9
///
/// Solution: Prepare a vector<int> of size w x h and fill
/// it in circular fashion as given in problem statement
#include <iostream>
#include <cstdlib>
#include <vector>
using namespace std;

int main(int argc, char *const *argv) {
  int w = 3, h = 3;
  if(argc != 3) {
    cout << "Bad arguments" << endl;
  } else {
    w = atoi(argv[1]);
    h = atoi(argv[2]);
  }

#define mat(X,Y) vmat[X+Y*w]
  vector<int> vmat(w*h);
  int num = 0;
  const int mx = w * h;
  if(w < 0 || mx < 0) return -3;
  int off = 0, wLimit = w - 1, hLimit = h - 1;
#define SET(X,Y) do { if(!mat(X,Y)) mat(X,Y) = ++num; } while(false)
//#define SET(X,Y) do { if(!mat(X,Y)) mat(X,Y) = ++num; cout << '(' << X << ',' << Y << ')' << num << endl; } while(false)
  while( (wLimit - off) > 0 && (hLimit - off) > 0) {
	  for(int i = off; i < wLimit; ++i) SET(i,off);
	  for(int i = off; i < hLimit; ++i) SET(wLimit,i);
	  for(int i = wLimit; i > off; --i) SET(i,hLimit);
	  for(int i = hLimit; i > off; --i) SET(off,i);
	  ++off, --wLimit, --hLimit;
  }
  if(wLimit == off) {
	  for(int i = off; i <= hLimit; ++i) SET(off, i);
  }
  if(hLimit == off) {
	  for(int i = off; i <= wLimit; ++i) SET(i, off);
  }
  //assert(num == w * h);

  for(int j = 0; j < h; ++j) {
    for(int i = 0; i < w; ++i) {
      cout << mat(i,j) << '\t';
    }
    cout << endl;
  }
}

// EOF

Bad arguments
1	2	3	
8	9	4	
7	6	5