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  1. #include <stdio.h>
  2. //a{n} = -6a{n-1} -9a{n-2}, a{1}=1, a{2}=2(再帰あり版)
  3.  
  4. int c;
  5.  
  6.  
  7. int rec(int n){
  8.     c++;
  9.  
  10.     if (n == 1){
  11.         return 1;
  12.     }
  13.     else if (n == 2){
  14.         return 2;
  15.     }
  16.     else{
  17.         return -6 * rec(n-1) - 9 * rec(n-2);
  18.     }
  19.     }
  20.  
  21. int main(void) {
  22.     int n = 5;
  23.     printf("数列a%dの値は%d\n", n, rec(n));
  24.     printf("このときrecの呼び出し回数は%d\n", c);
  25. 	return 0;
  26. }
  27.  
  28.  
Success #stdin #stdout 0s 5320KB
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stdin
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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/RqRM1H
language:
C (gcc 8.3)
created:
5 days ago
visibility:
public

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