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  1. #include <stdio.h>
  2.  
  3. /* This is a tail-recursive version :-D */
  4. void shift_replace_rec(int *A, unsigned int len, unsigned int delta)
  5. {
  6.     if (delta > 0)
  7.     {
  8.         unsigned int i = len-1;
  9.  
  10.         /* Get the last element to eventually swap it with the first. */
  11.         unsigned int temp = A[i];
  12.  
  13.         /* Shift everything one block to the right. */
  14.         for (; i > 0; --i)
  15.         {
  16.             A[i] = A[i-1];
  17.         }
  18.  
  19.         /* Last element is now the first element. */
  20.         A[i] = temp;
  21.  
  22.         /* Recurse! */
  23.         shift_replace_rec(A, len, delta-1);
  24.     }
  25. }
  26.  
  27. void print_array(const int *A, const unsigned int len)
  28. {
  29.     int i;
  30.     for (i = 0; i < 10; ++i)
  31.     {
  32.         printf("%d", A[i]);
  33.     }
  34.     putchar('\n');
  35. }
  36.  
  37. int main(int argc, char *argv[])
  38. {
  39.     int A[] = {0,1,2,3,4,5,6,7,8,9};
  40.     print_array(A, 10);
  41.     puts("Shifting by 3...");
  42.     shift_replace_rec(A, 10, 3);
  43.     print_array(A, 10);
  44.     puts("Shifting by 7... (Should be the original order now)");
  45.     shift_replace_rec(A, 10, 7);
  46.     print_array(A, 10);
  47.     return 0;
  48. }
Success #stdin #stdout 0.01s 1720KB
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stdin
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Standard input is empty
stdout
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0123456789
Shifting by 3...
7890123456
Shifting by 7... (Should be the original order now)
0123456789
https://ideone.com/q1nG6
language:
C (gcc 8.3)
created:
14 years ago
visibility:
public

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