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  1. #include <stdio.h>
  2.  
  3. int f(int n,int a[][n],int*b){int d=0,j=0,k=0,s=0,m=n-1,f=0;for(int i=0;i<n*n;i++,s++){if(s==m){d++,d%=4,s=0,f++;if(f%3==0)m--,f=1;}b[i]=!d?a[j][k++]:d==1?a[j++][k]:d==2?a[j][k--]:a[j--][k];}}
  4.  
  5. int main(void) {
  6. 	#define N 5
  7.  
  8. 	/* The input array. */
  9. 	#if N == 0
  10. 		int a[1][1];
  11. 	#elif N == 1
  12. 		int a[N][N] = {{1}};
  13. 	#elif N == 2
  14. 		int a[N][N] = {{1, 2}, {4, 3}};
  15. 	#elif N == 3
  16. 		int a[N][N] = {{1, 2,  3}, {8, 9,  4}, {7, 6,  5}};
  17. 	#elif N == 4
  18. 		int a[N][N] = {{ 1,  2,  3, 4}, {12, 13, 14, 5}, {11, 16, 15, 6}, {10,  9,  8, 7}};
  19. 	#elif N == 5
  20. 		int a[N][N] = {{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}};
  21. 	#endif
  22.  
  23. 	/* The output array. */
  24. 	#if N != 0
  25. 		int b[N*N];
  26. 	#else
  27. 		int b[1];
  28. 	#endif
  29.  
  30. 	/* Process. */
  31. 	f(N, a, b);
  32.  
  33. 	/* Print the result. */
  34. 	#if N != 0
  35. 		for (size_t i = 0; i < N*N; i++)
  36. 			printf("%d ", b[i]);
  37. 	#endif
  38. }
  39.  
Success #stdin #stdout 0s 9424KB
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https://ideone.com/eiTw4K
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

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