C语言代码：求1/1+1/2+2/3+3/5+5/8...前n项和

#include <stdio.h>

int main() {
    int n;
    scanf("%d", &n);
    double sum = 0;
    double a = 1, b = 1; // 前两项
    for (int i = 1; i <= n; i++) {
        sum += a / b;
        double tmp = a + b;
        a = b;
        b = tmp;
    }
    printf("%.3lf", sum);
    return 0;
}