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  1. #include <stdio.h>
  2. #define N_ROWS 5
  3. #define N_COLS 3
  4.  
  5. void print_spiral(int a[N_ROWS][N_COLS])
  6. {
  7.     enum {up, down, left, right} direction = right;
  8.     int up_limit = 0,
  9.         down_limit = N_ROWS - 1,
  10.         left_limit = 0,
  11.         right_limit = N_COLS - 1,
  12.         downcount = N_ROWS * N_COLS,
  13.         row = 0,
  14.         col = 0;
  15.  
  16.     while(printf("%d ", a[row][col]) && --downcount)
  17.         if(direction == right)
  18.         {
  19.             if(++col > right_limit)
  20.             {
  21.                 --col;
  22.                 direction = down;
  23.                 ++up_limit;
  24.                 ++row;
  25.             }
  26.         }
  27.         else if(direction == down)
  28.         {
  29.             if(++row > down_limit)
  30.             {
  31.                 --row;
  32.                 direction = left;
  33.                 --right_limit;
  34.                 --col;
  35.             }
  36.         }
  37.         else if(direction == left)
  38.         {
  39.             if(--col < left_limit)
  40.             {
  41.                 ++col;
  42.                 direction = up;
  43.                 --down_limit;
  44.                 --row;
  45.             }
  46.         }
  47.         else /* direction == up */
  48.             if(--row < up_limit)
  49.             {
  50.                 ++row;
  51.                 direction = right;
  52.                 ++left_limit;
  53.                 ++col;
  54.             }
  55. }
  56.  
  57. int main()
  58. {
  59.     int a[N_ROWS][N_COLS] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
  60.     print_spiral(a);
  61.     return 0;
  62. }
Success #stdin #stdout 0.02s 1720KB
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1 2 3 6 9 12 15 14 13 10 7 4 5 8 11
https://ideone.com/UN1y2
language:
C (gcc 8.3)
created:
12 years ago
visibility:
secret

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