Greater Integers

#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>
#include <fstream>
#include <sstream>
#include <bitset>
#include <cassert>
#include <functional>
#include <cstring>
#include <ctime>
#include <cmath>
#include <set>
#include <map>
#include <algorithm>
#define sec second
#define fir first
#define pb push_back
#define mp make_pair
#define REP(i , n) for (int i = 0 ; i < (n) ; i++)
#define BACK(i , n) for (int i = (n) - 1 ; i >= 0 ; i--)
using namespace std;
using vi = vector<int>;
using vii = vector<vi>;
using pii = pair<int , int>;
using ll = long long;
using ld = long double;
const int MAX = 1e9 , MIN = - MAX , MOD = 1e9 + 7;
const ll MAX_LL = 1e18 , MIN_LL = -MAX_LL;
int main(){
    int T;
    cin >> T;
    vector<ll> vec;
    for (int sz = 1 ; sz <= 18 ; ++sz)
        for (char i = '1' ; i <= '9' ; ++i){
            ll now;
            stringstream(string(sz , i)) >> now;
            vec.push_back(now);
        }
    while(T--){
        ll z;
        cin >> z;
        auto it = lower_bound(begin(vec) , end(vec) , z);
        cout << (*it  == z ? *(it + 1) : *it)  << endl;
    }
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: WRONG ANSWER