python/TangDou/XiTi/1457.cpp

#include <bits/stdc++.h>

using namespace std;

//递归，TLE
int fib(int n) {
    if (n == 1) return 1;
    if (n == 2) return 1;
    return fib(n - 1) % 9997 + fib(n - 2) % 9997;
}

//while循环
int fib2(int n) {
    if (n == 1) return 1;
    if (n == 2) return 1;
    int i = 3;
    int a = 1, b = 1;
    while (i <= n) {
        int c = a % 9997 + b % 9997;
        a = b % 9997;
        b = c % 9997;
        i++;
    }
    return b;
}

int main() {
    int n;
    cin >> n;
    cout << fib2(n) << endl;
    return 0;
}