fork(1) download
copy 
  1. #include <stdio.h>
  2.  
  3. int f(int n,int a[][n],int*b){static d,j,k,s,f,i,m;for(m=n-1;i<n*n;i++,s++)s==m?d++,d%=4,s=0,f++,f%3==0?m--,f=1:m:m,b[i]=!d?a[j][k++]:d==1?a[j++][k]:d==2?a[j][k--]:a[j--][k];}
  4.  
  5. /* The spiral function from RosettaCode. */
  6. int spiral(int w, int h, int x, int y) {
  7. 	return y ? w + spiral(h - 1, w, y - 1, w - x - 1) : x;
  8. }
  9.  
  10. int main(void) {
  11. 	#define N 5
  12.  
  13. 	/* Generation of the input array. */	
  14. 	#if N == 0
  15. 		int a[1][1];
  16. 	#else
  17. 		int a[N][N];
  18.  
  19. 		for (size_t i = 0; i < N; i++) {
  20. 			for (size_t j = 0; j < N; j++) {
  21. 				a[i][j] = spiral(N, N, j, i) + 1;
  22. 				printf("%4d", a[i][j]);
  23. 			}
  24.  
  25. 			putchar('\n');
  26. 		}
  27. 	#endif
  28.  
  29. 	/* Declaration of the output array. */
  30. 	#if N != 0
  31. 		int b[N*N];
  32. 	#else
  33. 		int b[1];
  34. 	#endif
  35.  
  36. 	/* Process. */
  37. 	f(N, a, b);
  38.  
  39. 	/* Print the result. */
  40. 	#if N != 0
  41. 		putchar('\n');
  42. 		for (size_t i = 0; i < N*N; i++)
  43. 			printf("%d ", b[i]);
  44. 	#endif
  45. }
  46.  
Success #stdin #stdout 0s 9424KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
   1   2   3   4   5
  16  17  18  19   6
  15  24  25  20   7
  14  23  22  21   8
  13  12  11  10   9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
https://ideone.com/7my1YS
StackOverflow's code golf (the fourth version).
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!