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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.  
  5. int rec(int n){
  6. 	c++;
  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. int main(void) {
  18.     int n = 5;
  19.     printf("数列a%dの値は%d\n", n, rec(n));
  20.     printf("この時recが呼び出された回数は%d\n", c);
  21. 	return 0;
  22. }
  23.  
  24.  
Success #stdin #stdout 0.01s 5284KB
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Standard input is empty
stdout
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数列a5の値は-459
この時recが呼び出された回数は9
https://ideone.com/0aGSEJ
language:
C (gcc 8.3)
created:
18 hours ago
visibility:
public

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