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  1. #include <assert.h>
  2. #include <stdio.h>
  3. #include <stdint.h>
  4. #include <stdlib.h>
  5.  
  6. int ack_recursive(int m, int n) {
  7.     if (m == 0) {
  8.         return n + 1;
  9.     }
  10.  
  11.     if (n == 0) {
  12.         return ack_recursive(m - 1, 1);
  13.     }
  14.  
  15.     return ack_recursive(m - 1, ack_recursive(m, n - 1));
  16. }
  17.  
  18. int ack_nonrecursive(int m, int n, int *status) {
  19.     int value[n];
  20.     size_t size = 0;
  21.  
  22.     for (;;) {
  23.         if (m == 0) {
  24.             n++;
  25.             if (size-- == 0) {
  26.                 *status = EXIT_SUCCESS;
  27.                 break;
  28.             }
  29.             assert(size < sizeof value / sizeof *value);
  30.             m = value[size];
  31.             continue;
  32.         }
  33.  
  34.         if (n == 0) {
  35.             m--;
  36.             n = 1;
  37.             continue;
  38.         }
  39.  
  40.         size_t index = size++;
  41.         assert(index < sizeof value / sizeof *value);
  42.         value[index] = m - 1;
  43.         n--;
  44.     }
  45.  
  46.     return n;
  47. }
  48.  
  49. int main(void) {
  50.     for (int m = 0; m < 2; m++) {
  51.         for (int n = 0; n < 2; n++) {
  52.             int status;
  53.             assert(ack_recursive(m, n) == ack_nonrecursive(m, n, &status) && status == EXIT_SUCCESS);
  54.         }
  55.     }
  56. }
Success #stdin #stdout 0s 9288KB
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Standard input is empty
stdout 
Standard output is empty
https://ideone.com/r58OOG
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

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