Greater Integers

input/code.cpp: In function 'int main()':
input/code.cpp:20:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while (at < dig.size() and dig[at] == dig[0]) ++at;
            ~~~^~~~~~~~~~~~
input/code.cpp:21:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (at == dig.size()) {
         ~~~^~~~~~~~~~~~~
input/code.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i <= dig.size(); ++i) putchar('1');
                         ~~^~~~~~~~~~~~~
input/code.cpp:26:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < dig.size(); ++i) printf("%d", dig[0] + 1);
                         ~~^~~~~~~~~~~~
input/code.cpp:31:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for (int i = 0; i < dig.size(); ++i) printf("%d", who);...

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int t; ll n;

int main() {
  cin >> t;
  while (t--) {
    cin >> n;
    vector <int> dig;
    while (n) {
      dig.emplace_back(n % 10);
      n /= 10;
    }
    reverse(dig.begin(), dig.end());
    int at = 0;
    while (at < dig.size() and dig[at] == dig[0]) ++at;
    if (at == dig.size()) {
      if (dig[0] == 9) {
        for (int i = 0; i <= dig.size(); ++i) putchar('1');
        puts("");
      } else {
        for (int i = 0; i < dig.size(); ++i) printf("%d", dig[0] + 1);
        puts("");  
      }
    } else {
      int who = (dig[at] > dig[0]) ? dig[0] + 1 : dig[0];
      for (int i = 0; i < dig.size(); ++i) printf("%d", who);
      puts("");
    }
  }
  return 0;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED