题解（不用数组和递归）

AC代码

#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    scanf("%d", &n);
    int a = 1, b = 0, c; 
    for (int i = 2; i <= n; i++) {
        c = a + b;
        b = a;
        a = c;
    }
    printf("%d", c);
    return 0;
}