Problem p01829 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstdio>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <tuple>
#include <utility>
#include <vector>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef vector<ll> V;
typedef complex<double> Point;

#define PI acos(-1.0)
#define EPS 1e-10
const ll INF = 1e12;
const ll MOD = 1e9 + 7;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define rep(i, N) for (int i = 0; i < (N); i++)
#define ALL(s) (s).begin(), (s).end()
#define EQ(a, b) (abs((a) - (b)) < EPS)
#define EQV(a, b) (EQ((a).real(), (b).real()) && EQ((a).imag(), (b).imag()))
#define fi first
#define se second
#define N_SIZE (1LL << 20)
#define NIL -1

ll sq(ll num) { return num * num; }
ll mod_pow(ll x, ll n) {
  if (n == 0)
    return 1;
  if (n == 1)
    return x % MOD;
  ll res = sq(mod_pow(x, n / 2));
  res %= MOD;
  if (n % 2 == 1) {
    res *= x;
    res %= MOD;
  }
  return res;
}
ll mod_add(ll a, ll b) { return (a + b) % MOD; }
ll mod_sub(ll a, ll b) { return (a - b + MOD) % MOD; }
ll mod_mul(ll a, ll b) { return a * b % MOD; }

string s;
vector<int> vi;

int main() {
  cin >> s;
  ll n;
  stringstream ss;
  ss << s;
  ss >> n;
  ss.clear();
  rep(i, 10) vi.push_back(i);
  sort(ALL(vi));
  ll g = 0;
  ll ans = 0;
  ll p = pow(10, s.size());
  do {
    ll num = 0;
    rep(i, s.size()) {
      num *= 10;
      num += vi[i];
    }
    if (g < min((ll)abs(num - n), (ll)(p - abs(num - n)))) {
      g = min((ll)abs(num - n), (ll)(p - abs(num - n)));
      ans = num;
    }
  } while (next_permutation(ALL(vi)));
  string a;
  ss << ans;
  ss >> a;
  reverse(ALL(a));
  while (a.size() != s.size())
    a += "0";
  reverse(ALL(a));
  rep(i, a.size()) cout << a[i];
  cout << endl;
}


Error: 0

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstdio>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <tuple>
#include <utility>
#include <vector>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef vector<ll> V;
typedef complex<double> Point;

#define PI acos(-1.0)
#define EPS 1e-10
const ll INF = 1e12;
const ll MOD = 1e9 + 7;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define rep(i, N) for (int i = 0; i < (N); i++)
#define ALL(s) (s).begin(), (s).end()
#define EQ(a, b) (abs((a) - (b)) < EPS)
#define EQV(a, b) (EQ((a).real(), (b).real()) && EQ((a).imag(), (b).imag()))
#define fi first
#define se second
#define N_SIZE (1LL << 20)
#define NIL -1

ll sq(ll num) { return num * num; }
ll mod_pow(ll x, ll n) {
  if (n == 0)
    return 1;
  if (n == 1)
    return x % MOD;
  ll res = sq(mod_pow(x, n / 2));
  res %= MOD;
  if (n % 2 == 1) {
    res *= x;
    res %= MOD;
  }
  return res;
}
ll mod_add(ll a, ll b) { return (a + b) % MOD; }
ll mod_sub(ll a, ll b) { return (a - b + MOD) % MOD; }
ll mod_mul(ll a, ll b) { return a * b % MOD; }

string s;
vector<int> vi;

int main() {
  cin >> s;
  ll n = stoi(s);
  rep(i, 10) vi.push_back(i);
  sort(ALL(vi));
  ll g = 0;
  ll ans = 0;
  ll p = pow(10, s.size());
  do {
    ll num = 0;
    rep(i, s.size()) {
      num *= 10;
      num += vi[i];
    }
    if (g < min((ll)abs(num - n), (ll)(p - abs(num - n)))) {
      g = min((ll)abs(num - n), (ll)(p - abs(num - n)));
      ans = num;
    }
  } while (next_permutation(ALL(vi)));
  stringstream ss;
  string a;
  ss << ans;
  ss >> a;
  reverse(ALL(a));
  while (a.size() != s.size())
    a += "0";
  reverse(ALL(a));
  rep(i, a.size()) cout << a[i];
  cout << endl;
}