#include <stdio.h>
//a{n} = 2a{n-1} + a{n-2}, a{1}=2, a{2}=3(再帰なし版)
int c;
int main(void) {
c++;
int n = 5;
int a, b = 3, c = 2;
for(int i = 3; i <= n; i++){
a = 2*b + c;
c=b;
b=a;
}
printf("このときrecの呼び出し回数は%d",c
); return 0;
}
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