Problem p02670 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// #include <ext/pb_ds/detail/standard_policies.hpp>
// using namespace __gnu_pbds;
using namespace std;
// template <typename T>
// using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,
//     tree_order_statistics_node_update>;

// #pragma GCC optimize("Ofast")
// #pragma GCC target("avx,avx2,fma")
// #pragma GCC optimization ("unroll-loops")
typedef long long int ll;
const ll N = 1e6;
// const ll m = 1e9 + 7;
// const ll inf= 1e14;
const ll mod = 1e9 + 7;
const ll INF = 1e14;
#define x first
#define y second
#define pb push_back
#define mp make_pair
#define pld pair<ld, ld>
#define pll pair<ll, ll>
#define pii pair<int, int>
#define ld long double
ll powm(ll a, ll b) {
  a = a % mod;
  ll res = 1;
  while (b) {
    if (b & 1)
      res = (res * a) % mod;
    a = (a * a) % mod;
    b >>= 1;
  }
  return res;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
  freopen("error.txt", "w", stderr);
#endif
  ll t = 1;
  // cin>>t;
  while (t--) {
    ll n;
    cin >> n;
    ll p[n * n];
    ll dp[n][n];
    bool is[n][n];
    for (int i = 0; i < n * n; i++) {
      cin >> p[i];
    }
    for (ll i = 0; i < n; i++) {
      for (ll j = 0; j < n; j++) {
        dp[i][j] = min(i, n - i - 1);
        dp[i][j] = min(dp[i][j], j);
        dp[i][j] = min(dp[i][j], n - j - 1);
        is[i][j] = 1;
      }
    }
    ll ans = 0;
    queue<pii> q;
    for (int i = 0; i < n * n; i++) {
      p[i]--;
      ll x = p[i] / n, y = p[i] % n;
      // cout<<x<<" "<<y<<'\\n';
      ans += dp[x][y];
      q.push(mp(x, y));
      is[x][y] = 0;
      while (!q.empty()) {
        pii v = q.front();
        q.pop();
        if (v.x > 0) {
          if (dp[v.x][v.y] + is[v.x][v.y] < dp[v.x - 1][v.y]) {
            dp[v.x - 1][v.y] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x - 1, v.y));
          }
        }
        if (v.x < n - 1) {
          if (dp[v.x][v.y] + is[v.x][v.y] < dp[v.x + 1][v.y]) {
            dp[v.x + 1][v.y] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x + 1, v.y));
          }
        }
        if (v.y < n - 1) {
          if (dp[v.x][v.y] + is[v.x][v.y] < dp[v.x][v.y + 1]) {
            dp[v.x][v.y + 1] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x, v.y + 1));
          }
        }
        if (v.y > 0) {
          if (dp[v.x][v.y] + is[v.x][v.y] < dp[v.x][v.y - 1]) {
            dp[v.x][v.y - 1] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x, v.y - 1));
          }
        }
      }
      // for(ll i = 0;i<n;i++){
      //     for(ll j = 0;j<n;j++){
      //         cout<<dp[i][j]<<" ";
      //     }
      //     cout<<'\\n';
      // }
      // cout<<'\\n';
    }
    cout << ans << '\\n';
  }
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// #include <ext/pb_ds/detail/standard_policies.hpp>
// using namespace __gnu_pbds;
using namespace std;
// template <typename T>
// using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,
//     tree_order_statistics_node_update>;

// #pragma GCC optimize("Ofast")
// #pragma GCC target("avx,avx2,fma")
// #pragma GCC optimization ("unroll-loops")
typedef long long int ll;
const ll N = 1e6;
// const ll m = 1e9 + 7;
// const ll inf= 1e14;
const ll mod = 1e9 + 7;
const ll INF = 1e14;
#define x first
#define y second
#define pb push_back
#define mp make_pair
#define pld pair<ld, ld>
#define pll pair<ll, ll>
#define pii pair<int, int>
#define ld long double
ll powm(ll a, ll b) {
  a = a % mod;
  ll res = 1;
  while (b) {
    if (b & 1)
      res = (res * a) % mod;
    a = (a * a) % mod;
    b >>= 1;
  }
  return res;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
  freopen("error.txt", "w", stderr);
#endif
  ll t = 1;
  // cin>>t;
  while (t--) {
    ll n;
    cin >> n;
    ll p[n * n];
    ll dp[n][n];
    bool is[n][n];
    for (int i = 0; i < n * n; i++) {
      cin >> p[i];
    }
    for (ll i = 0; i < n; i++) {
      for (ll j = 0; j < n; j++) {
        dp[i][j] = min(i, n - i - 1);
        dp[i][j] = min(dp[i][j], j);
        dp[i][j] = min(dp[i][j], n - j - 1);
        is[i][j] = 1;
      }
    }
    ll ans = 0;
    queue<pii> q;
    for (int i = 0; i < n * n; i++) {
      p[i]--;
      ll x = p[i] / n, y = p[i] % n;
      // cout<<x<<" "<<y<<'\\n';
      ans += dp[x][y];
      q.push(mp(x, y));
      is[x][y] = 0;
      while (!q.empty()) {
        pii v = q.front();
        q.pop();
        if (v.x > 0) {
          if (dp[v.x][v.y] < dp[v.x - 1][v.y]) {
            dp[v.x - 1][v.y] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x - 1, v.y));
          }
        }
        if (v.x < n - 1) {
          if (dp[v.x][v.y] < dp[v.x + 1][v.y]) {
            dp[v.x + 1][v.y] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x + 1, v.y));
          }
        }
        if (v.y < n - 1) {
          if (dp[v.x][v.y] < dp[v.x][v.y + 1]) {
            dp[v.x][v.y + 1] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x, v.y + 1));
          }
        }
        if (v.y > 0) {
          if (dp[v.x][v.y] < dp[v.x][v.y - 1]) {
            dp[v.x][v.y - 1] = dp[v.x][v.y] + is[v.x][v.y];
            q.push(mp(v.x, v.y - 1));
          }
        }
      }
      // for(ll i = 0;i<n;i++){
      //     for(ll j = 0;j<n;j++){
      //         cout<<dp[i][j]<<" ";
      //     }
      //     cout<<'\\n';
      // }
      // cout<<'\\n';
    }
    cout << ans << '\\n';
  }
}