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  1. #include <iostream>
  2. #include <map>
  3.  
  4. int const N = 10000000;
  5. class mypair {
  6. public:
  7.   int m, n;
  8.   mypair(int m, int n) { this->m = m; this->n = n; }
  9.   bool operator<(const mypair &r) const {
  10.     return (this->m * N + this->n) < (r.m * N + r.n);
  11.   }
  12. };
  13.  
  14. std::map<mypair, int> mpair;
  15. static int c = 0;
  16. static int xmax = 0;
  17. int ack(std::map<mypair, int> &mpair, int m, int n, int x) {
  18.   c++;
  19.   if (xmax < x)
  20.     xmax = x;
  21.  
  22.   if (mpair.find(mypair(m, n)) != mpair.end()) {
  23. /*    goto label; */
  24.     int r;
  25.     r = mpair[mypair(m, n)];
  26.     return r;
  27.   } else {
  28.   label:
  29.     int r;
  30.     if (m == 0)
  31.       r = n + 1;
  32.     else if (n == 0)
  33.       r = ack(mpair, m - 1, 1, x + 1);
  34.     else { r = ack(mpair, m - 1, ack(mpair, m, n - 1, x + 1), x + 1); }
  35.     mpair[mypair(m, n)] = r;
  36.     return r;
  37.   } 
  38. }
  39.  
  40. int main() {
  41.   std::cout << ack(mpair, 4, 1, 0) << std::endl;
  42.   std::cout << "calls:" << c << ", nest:" << xmax << std::endl;
  43.   return 0;
  44. }
  45. /* end */
  46.  
Success #stdin #stdout 0.1s 9040KB
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Standard input is empty
stdout
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65533
calls:196625, nest:16388
https://ideone.com/OJjfxv
language:
C++ 4.3.2 (gcc-4.3.2)
created:
8 years ago
visibility:
public

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