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  1. #include <stdio.h>
  2. //練習問題G
  3.  
  4. int func(int n){
  5.     int a, b=2, c=1;
  6.  
  7.     if (n == 1) return 1;  
  8.     else if (n == 2) return 2;  
  9.  
  10.     for(int i=3;i<=n;i++){
  11.     	a= -2 * b + 2 * c;  
  12.     	c=b;
  13.     	b=a;
  14.     }
  15. return a;
  16.  
  17. }
  18. int main(void) {
  19. 	int n = 3;
  20.     printf("数列anについて, n=%dのときの値は%d\n", n, func(n));
  21. 	return 0;
  22. }
  23.  
Success #stdin #stdout 0s 5320KB
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Standard input is empty
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数列anについて, n=3のときの値は-2
https://ideone.com/a2q9Rb
language:
C (gcc 8.3)
created:
14 days ago
visibility:
public

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