Asking for Help: #387. BFIBONACCI

for (int i = 2; i <= 5000; i++)

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

void addBigNum(string& res, string a, string b){
	int n = max(a.length(), b.length());
    res.resize(n);
    while (a.length() < n) a = "0" + a;
    while (b.length() < n) b = "0" + b;
    int cr = 0;
    for (int i = n - 1; i >= 0; i--){
        cr += a[i] + b[i] - 48*2;
        res[i] = cr % 10 + '0';
		cr /= 10;
    }
    if (cr) res = "1" + res;
}

const int maxn = 10001;
string F[maxn];
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    
    F[0] = "1";
    F[1] = "1";
    for (int i = 2; i < maxn; i++){
        addBigNum(F[i], F[i-1], F[i-2]);
    }
    int n;
    cin >> n;
    while (cin >> n) cout << F[n] << "\n";
}