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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. int c=0;
  4. int rec(int n){
  5. 	c++;
  6.  
  7. 	if(n==1){
  8. 		return 1;
  9. 	}
  10. 	else if(n==2){
  11. 		return 2;
  12. 	}
  13. 	else{
  14. 		return -6*rec(n-1)-9*rec(n-2);
  15. 	}
  16.  
  17.  
  18.  
  19. }
  20.  
  21. int main(void) {
  22.     int n;
  23.     scanf("%d",&n);
  24.  
  25.     printf("数列a%dの値は%d\n", n, rec(n));
  26.  
  27.     printf("このときrecの呼び出し回数は%d\n",c);
  28.  
  29. 	return 0;
  30. }
  31.  
  32.  
Success #stdin #stdout 0s 5320KB
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5
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/nRLtXf
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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