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  1. #include <stdio.h>
  2.  
  3. int c = 0;
  4.  
  5. int rec(int n) {
  6.     c++;
  7.  
  8.     if (n == 1)
  9.         return 1;
  10.     else if (n == 2)
  11.         return 2;
  12.     else
  13.         return -6 * rec(n - 1) - 9 * rec(n - 2);
  14. }
  15.  
  16. int main(void) {
  17.     int n = 5;   // 実行例に合わせるなら5
  18.  
  19.     c = 0;       // 念のためリセット
  20.     printf("数列a%dの値は%d\n", n, rec(n));
  21.     printf("このときrecの呼び出し回数は%d\n", c);
  22.  
  23.     return 0;
  24. }
Success #stdin #stdout 0.01s 5312KB
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Standard input is empty
stdout
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数列a5の値は-459
このときrecの呼び出し回数は9
https://ideone.com/NMsCwf
language:
C (gcc 8.3)
created:
2 days ago
visibility:
public

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