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  1. #include <stdio.h>
  2. int c=0;
  3.  
  4. // a[n] = -6a[n-1] - 9a[n-2], a[1]=1, a[2]=2 (再帰あり版)
  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.  
  18. int main(void) {
  19.     int n = 5;
  20.  
  21.     printf("数列a%dの値は%d\n", n, rec(n));
  22.     printf("recの呼び出し回数は:%d\n",c);
  23.     return 0;
  24. }
  25.  
Success #stdin #stdout 0.01s 5320KB
comments (?)
stdin 
Standard input is empty
stdout 
数列a5の値は-459
recの呼び出し回数は:9
https://ideone.com/05m1cO
language:
C (gcc 8.3)
created:
4 days ago
visibility:
public

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