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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;
  4. int rec(int n){
  5. 	c++;
  6. 	if(n == 1){
  7. 		return 1;
  8. 	}
  9. 	else if(n == 2){
  10. 		return 2;
  11. 	}
  12. 	else{
  13. 	return -6*rec(n-1)-9*rec(n-2);
  14. 	}
  15.  
  16. }
  17.  
  18. int main(void) {
  19.     int n = 4;
  20.     printf("数列a%dの値は%d\n", n, rec(n));
  21.     printf("recの呼び出し回数は%d\n",c);
  22. 	return 0;
  23. }
  24.  
  25.  
Success #stdin #stdout 0s 5296KB
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Standard input is empty
stdout
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数列a4の値は108
recの呼び出し回数は5
https://ideone.com/ZV6TTM
language:
C (gcc 8.3)
created:
4 days ago
visibility:
public

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