LCR 126
https://leetcode.cn/problems/fei-bo-na-qi-shu-lie-lcof/description/
难度：简单
高频面试题汇总：https://www.yuweihung.com/posts/2025/lc-hot/
class Solution {
public:
int fib(int n) {
if (n == 0) {
return 0;
}
if (n == 1) {
return 1;
}
int MOD = 1e9 + 7;
int f0 = 0, f1 = 1;
int f2;
for (int i = 2; i <= n; i++) {
f2 = (f0 + f1) % MOD;
f0 = f1;
f1 = f2;
}
return f2;
}
};