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  1. #include <stdio.h>
  2. int c = 0;
  3.  
  4. // a_n = -6a_(n-1) - 9a_(n-2), a1=1, a2=2
  5. int rec(int n){
  6.     c++; 
  7.  
  8.     if (n == 1){
  9.         return 1;
  10.     }
  11.     else if (n == 2){
  12.         return 2;
  13.     }
  14.     else{
  15.         return -6 * rec(n - 1) - 9 * rec(n - 2);
  16.     }
  17.     }
  18. int main(void){
  19.      int n = 5;
  20.     printf("数列a%dの値は%d\n", n, rec(n));
  21.     printf("この時recの呼び出し回数は%d回",c);
  22.     return 0;
  23. }
  24.  
Success #stdin #stdout 0s 5320KB
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Standard input is empty
stdout
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数列a5の値は-459
この時recの呼び出し回数は9回
https://ideone.com/iNqiWx
language:
C (gcc 8.3)
created:
3 days ago
visibility:
public

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