Submission

Score: 100

User: IKKIWPR

Problemset: อนุกรม

Language: cpp

Time: 0.002 second

Submitted On: 2026-10-08 18:08:57

#include <iostream>
#include <string>
using namespace std;

string add(const string &a, const string &b){
    string res = "";
    int i = a.size() - 1, j = b.size() - 1, carry = 0;
    while (i >= 0 || j >= 0 || carry){
        int sum = carry;
        if (i >= 0) sum += a[i--] - '0';
        if (j >= 0) sum += b[j--] - '0';
        res = char(sum % 10 + '0') + res;
        carry = sum / 10;
    }
    return res;
}

int main(){
    int n; cin >> n;
    string arr[105];
    arr[1] = "1";
    arr[2] = "1";
    for (int i = 3; i <= n; i++){
        arr[i] = add(arr[i-1], arr[i-2]);
    }
    cout << arr[n];
    return 0;
}