Problem p04016 (C++)

Buggy submission (status: Runtime Error):
/* Author : Aaryan Srivastava ^__^ */
#include <bits/stdc++.h>
#include <chrono>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <random>
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define rep(i, n) for (int i = 0; i < (n); i++)
#define repA(i, x, y) for (int i = (x); i <= (y); i++)
#define repD(i, x, y) for (int i = (x); i >= (y); i--)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define setval(a, val) memset(a, val, sizeof(a))
#define Randomize                                                              \
  mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define trav(x, a) for (auto &x : a)
#define sz(a) ((int)a.size())
typedef long long ll;
#define int ll
using namespace std;

const int N = 3e5 + 5;
const int mod = 1e9 + 7;
const ll inf = 1e18;
const int SZ = 101;
const long double eps = 1e-9;

using namespace __gnu_pbds;
using ordered_set = tree<int, null_type, less<int>, rb_tree_tag,
                         tree_order_statistics_node_update>;

typedef pair<int, int> pii;
typedef pair<int, pii> ipii;
typedef pair<pii, int> piii;
typedef unsigned long long ull;
typedef long double ld;

ll po(ll x, ll y, ll p = mod) {
  ll res = 1;
  x %= p;
  while (y > 0) {
    if (y & 1)
      res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}

int dsum(int b, int n) {
  if (n == 0)
    return 0;
  return dsum(b, n / b) + n % b;
}
bool chck(int b, int n, int s) {
  // cout << b << ' ' << dsum(b , n) << " " << s << '\n';
  return dsum(b, n) == s;
}

void solve() {
  int n, s;
  cin >> n >> s;
  if (s == n) {
    cout << n + 1;
    return;
  }

  int lst = 0;
  for (int i = 2; i * i <= n; ++i) {
    lst = i;
    if (chck(i, n, s)) {
      cout << i;
      return;
    }
  }
  int ans = inf;
  for (int p = 1; p * p <= n; ++p) {
    if ((n - s) % p)
      continue;
    int b = (n - s) / p + 1;
    if (chck(b, n, s))
      ans = min(ans, b);
  }
  // rep(j , 2)
  // if(chck(n + j , n , s)) ans = min(ans , n + j);
  cout << (ans == inf ? -1 : ans);
}

int32_t main(int32_t argc, char *argv[]) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int TC = 1, t = 0;
  // cin >> TC ;
  while (t++ < TC) {
    // cout << "Case #" << t << ": " ;
    solve();
    cout << "\n";
  }
  return 0;
}


Fixed submission:
/* Author : Aaryan Srivastava ^__^ */
#include <bits/stdc++.h>
#include <chrono>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <random>
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define rep(i, n) for (int i = 0; i < (n); i++)
#define repA(i, x, y) for (int i = (x); i <= (y); i++)
#define repD(i, x, y) for (int i = (x); i >= (y); i--)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define setval(a, val) memset(a, val, sizeof(a))
#define Randomize                                                              \
  mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define trav(x, a) for (auto &x : a)
#define sz(a) ((int)a.size())
typedef long long ll;
#define int ll
using namespace std;

const int N = 3e5 + 5;
const int mod = 1e9 + 7;
const ll inf = 1e18;
const int SZ = 101;
const long double eps = 1e-9;

using namespace __gnu_pbds;
using ordered_set = tree<int, null_type, less<int>, rb_tree_tag,
                         tree_order_statistics_node_update>;

typedef pair<int, int> pii;
typedef pair<int, pii> ipii;
typedef pair<pii, int> piii;
typedef unsigned long long ull;
typedef long double ld;

ll po(ll x, ll y, ll p = mod) {
  ll res = 1;
  x %= p;
  while (y > 0) {
    if (y & 1)
      res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}

int dsum(int b, int n) {
  if (n == 0)
    return 0;
  return dsum(b, n / b) + n % b;
}
bool chck(int b, int n, int s) {
  if (b < 2)
    return false;
  // cout << b << ' ' << dsum(b , n) << " " << s << '\n';
  return dsum(b, n) == s;
}

void solve() {
  int n, s;
  cin >> n >> s;
  if (s == n) {
    cout << n + 1;
    return;
  }

  int lst = 0;
  for (int i = 2; i * i <= n; ++i) {
    lst = i;
    if (chck(i, n, s)) {
      cout << i;
      return;
    }
  }
  int ans = inf;
  for (int p = 1; p * p <= n; ++p) {
    if ((n - s) % p)
      continue;
    int b = (n - s) / p + 1;
    if (chck(b, n, s))
      ans = min(ans, b);
  }
  // rep(j , 2)
  // if(chck(n + j , n , s)) ans = min(ans , n + j);
  cout << (ans == inf ? -1 : ans);
}

int32_t main(int32_t argc, char *argv[]) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int TC = 1, t = 0;
  // cin >> TC ;
  while (t++ < TC) {
    // cout << "Case #" << t << ": " ;
    solve();
    cout << "\n";
  }
  return 0;
}