Problem p02670 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef double ld;
// #define ll __int128
// #define int ll
// #define int ll
// #define char ll
#define double ld
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<vvc> vvvc;
typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.rbegin(), a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for (int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;

#ifdef MAX_HOME
#define cerr cout
#else
#define cerr                                                                   \\
  if (false)                                                                   \\
  cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";

template <class T0, class T1>
inline ostream &operator<<(ostream &out, pair<T0, T1> &a) {
  return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1>
inline istream &operator>>(istream &in, pair<T0, T1> &a) {
  return in >> a.first >> a.second;
}

template <class T0, class T1, class T2>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2, T3> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << ", " << get<3>(a) << "}";
}

template <class T> inline ostream &operator<<(ostream &out, vector<T> &a) {
  out << "[";
  fori(i, a.size()) out << a[i]
                        << vector<string>{", ", "]  "}[i + 1 == a.size()];
  return out;
}

void smain();

signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
#ifdef MAX_HOME
  freopen("input.txt", "r", stdin);
  clock_t start = clock();
#endif
  cout << setprecision(12) << fixed;
  smain();
#ifdef MAX_HOME
  cout << "\\n\\nTOTAL EXECUTION TIME: "
       << float(clock() - start) / CLOCKS_PER_SEC << endl;
#endif
  return 0;
}

vi di = {0, 0, -1, 1};
vi dj = {-1, 1, 0, 0};

void solve() {
  int n;
  cin >> n;

  vi p(n * n);
  fori(i, n * n) {
    cin >> p[i];
    p[i]--;
  }

  vvi d(n, vi(n, 0));
  vvi used(n, vi(n, 0));
  fori(i, n) {
    fori(j, n) { d[i][j] = min(min(i, n - i - 1), min(j, n - j - 1)) + 1; }
  }
  auto in_bound = [&](int i, int j) -> bool {
    return i >= 0 && i < n && j >= 0 && j < n;
  };

  auto change = function<void(int, int)>();
  change = [&](int i, int j) -> void {
    int ret = n * n;
    fori(dir, di.size()) {
      int ii = i + di[dir];
      int jj = j + dj[dir];
      if (in_bound(ii, jj))
        inmin(ret, d[ii][jj]);
      else
        ret = 0;
    }
    ret += !used[i][j];

    if (ret != d[i][j]) {
      assert(ret < d[i][j]);
      d[i][j] = ret;
      fori(dir, di.size()) {
        int ii = i + di[dir];
        int jj = j + dj[dir];
        if (in_bound(ii, jj))
          change(ii, jj);
      }
    }
  };

  int ans = 0;
  for (auto x : p) {
    int i = x / n, j = x % n;
    used[i][j] = 1;
    change(i, j);
    ans += d[i][j];
  }
  cout << ans << '\\n';
}

void smain() { solve(); }

Error: -6
e2c1271b-0dcf-4e18-b6c5-55920f0c10cc.out: /home/alex/Documents/bug-detection/input/Project_CodeNet/data/p02670/C++/s679827207.cpp:148: solve()::<lambda(int, int)>: Assertion `ret > d[i][j]' failed.


Fixed submission:

#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef double ld;
// #define ll __int128
// #define int ll
// #define int ll
// #define char ll
#define double ld
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<vvc> vvvc;
typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.rbegin(), a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for (int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;

#ifdef MAX_HOME
#define cerr cout
#else
#define cerr                                                                   \\
  if (false)                                                                   \\
  cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";

template <class T0, class T1>
inline ostream &operator<<(ostream &out, pair<T0, T1> &a) {
  return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1>
inline istream &operator>>(istream &in, pair<T0, T1> &a) {
  return in >> a.first >> a.second;
}

template <class T0, class T1, class T2>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2, T3> &a) {
  return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a)
             << ", " << get<3>(a) << "}";
}

template <class T> inline ostream &operator<<(ostream &out, vector<T> &a) {
  out << "[";
  fori(i, a.size()) out << a[i]
                        << vector<string>{", ", "]  "}[i + 1 == a.size()];
  return out;
}

void smain();

signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
#ifdef MAX_HOME
  freopen("input.txt", "r", stdin);
  clock_t start = clock();
#endif
  cout << setprecision(12) << fixed;
  smain();
#ifdef MAX_HOME
  cout << "\\n\\nTOTAL EXECUTION TIME: "
       << float(clock() - start) / CLOCKS_PER_SEC << endl;
#endif
  return 0;
}

vi di = {0, 0, -1, 1};
vi dj = {-1, 1, 0, 0};

void solve() {
  int n;
  cin >> n;

  vi p(n * n);
  fori(i, n * n) {
    cin >> p[i];
    p[i]--;
  }

  vvi d(n, vi(n, 0));
  vvi used(n, vi(n, 0));
  fori(i, n) {
    fori(j, n) { d[i][j] = min(min(i, n - i - 1), min(j, n - j - 1)); }
  }
  auto in_bound = [&](int i, int j) -> bool {
    return i >= 0 && i < n && j >= 0 && j < n;
  };

  auto change = function<void(int, int)>();
  change = [&](int i, int j) -> void {
    int ret = n * n;
    fori(dir, di.size()) {
      int ii = i + di[dir];
      int jj = j + dj[dir];
      if (in_bound(ii, jj))
        inmin(ret, d[ii][jj]);
      else
        ret = 0;
    }
    ret += !used[i][j];

    if (ret != d[i][j]) {
      assert(ret > d[i][j]);
      d[i][j] = ret;
      fori(dir, di.size()) {
        int ii = i + di[dir];
        int jj = j + dj[dir];
        if (in_bound(ii, jj))
          change(ii, jj);
      }
    }
  };

  int ans = 0;
  for (auto x : p) {
    int i = x / n, j = x % n;
    used[i][j] = 1;
    change(i, j);
    ans += d[i][j];
  }
  cout << ans << '\\n';
}

void smain() { solve(); }