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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=0;
  5. int rec(int n){
  6. 	if(n==1){
  7. 		c++;
  8. 		return 1;
  9. 	}
  10. 	else if(n==2){
  11. 		c++;
  12. 		return 2;
  13. 	}
  14. 	else{
  15. 		c++;
  16. 		return -6*rec(n-1)-9*rec(n-2);
  17. 	}
  18. }
  19.  
  20. int main(void) {
  21.     int n = 4;
  22.     printf("数列a%dの値は%d\n", n, rec(n));
  23. 	printf("このときrecの呼び出し回数は%d\n",c);
  24. 	return 0;
  25. }
  26.  
  27.  
Success #stdin #stdout 0s 5328KB
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Standard input is empty
stdout
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数列a4の値は108
このときrecの呼び出し回数は5
https://ideone.com/8bOVLi
language:
C (gcc 8.3)
created:
4 days ago
visibility:
public

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