Problem p02709 (C++) — buggy submission, verdict: Time Limit Exceeded

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// #include<ext/pb_ds/tag_and_trait.hpp>
// using namespace __gnu_pbds;
// #include<boost/multiprecision/cpp_int.hpp>
// namespace multiprecisioninteger = boost::multiprecision;
// using cint=multiprecisioninteger::cpp_int;
using namespace std;
using ll = long long;
#define double long double
using datas = pair<ll, ll>;
using ddatas = pair<double, double>;
using tdata = pair<ll, datas>;
using vec = vector<ll>;
using mat = vector<vec>;
using pvec = vector<datas>;
using pmat = vector<pvec>;
// using
// llset=tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>;
#define For(i, a, b) for (i = a; i < (ll)b; ++i)
#define bFor(i, b, a) for (i = b, --i; i >= (ll)a; --i)
#define rep(i, N) For(i, 0, N)
#define rep1(i, N) For(i, 1, N)
#define brep(i, N) bFor(i, N, 0)
#define brep1(i, N) bFor(i, N, 1)
#define all(v) (v).begin(), (v).end()
#define allr(v) (v).rbegin(), (v).rend()
#define vsort(v) sort(all(v))
#define vrsort(v) sort(allr(v))
#define endl "\\n"
#define eb emplace_back
#define print(v) cout << v << endl
#define printyes cout << "Yes" << endl
#define printno cout << "No" << endl
#define printYES cout << "YES" << endl
#define printNO cout << "NO" << endl
#define output(v)                                                              \\
  do {                                                                         \\
    bool f = 0;                                                                \\
    for (auto outi : v) {                                                      \\
      cout << (f ? " " : "") << outi;                                          \\
      f = 1;                                                                   \\
    }                                                                          \\
    cout << endl;                                                              \\
  } while (0)
#define matoutput(v)                                                           \\
  do {                                                                         \\
    for (auto outimat : v)                                                     \\
      output(outimat);                                                         \\
  } while (0)
const ll mod = 1000000007;
// const ll mod=998244353;
const ll inf = 1LL << 60;
const double PI = acos(-1);
const double eps = 1e-9;
template <class T> inline bool chmax(T &a, T b) {
  bool x = a < b;
  if (x)
    a = b;
  return x;
}
template <class T> inline bool chmin(T &a, T b) {
  bool x = a > b;
  if (x)
    a = b;
  return x;
}

void startupcpp() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}

double distance(ddatas x, ddatas y) {
  double a = x.first - y.first, b = x.second - y.second;
  return sqrt(a * a + b * b);
}

ll modinv(ll a) {
  ll b = mod, u = 1, v = 0, t;
  while (b) {
    t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  return (u + mod) % mod;
}

ll moddevide(ll a, ll b) { return (a * modinv(b)) % mod; }

vec modncrlistp, modncrlistm;

ll modncr(ll n, ll r) {
  if (n < r)
    return 0;
  ll i, size = modncrlistp.size();
  if (size <= n) {
    modncrlistp.resize(n + 1);
    modncrlistm.resize(n + 1);
    if (!size) {
      modncrlistp[0] = modncrlistm[0] = 1;
      size++;
    }
    For(i, size, n + 1) {
      modncrlistp[i] = modncrlistp[i - 1] * i % mod;
      modncrlistm[i] = modinv(modncrlistp[i]);
    }
  }
  return modncrlistp[n] * modncrlistm[r] % mod * modncrlistm[n - r] % mod;
}

ll modpow(ll a, ll n) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}

ll gcd(ll a, ll b) {
  if (!b)
    return a;
  return (a % b == 0) ? b : gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

ll countdigits(ll n) {
  ll ans = 0;
  while (n) {
    n /= 10;
    ans++;
  }
  return ans;
}

ll sumdigits(ll n) {
  ll ans = 0;
  while (n) {
    ans += n % 10;
    n /= 10;
  }
  return ans;
}
int main() {
  startupcpp();
  // int codeforces;cin>>codeforces;while(codeforces--){
  ll i, j, N, M;
  cin >> N;
  pvec v(N);
  mat dp(N + 1, vec(N + 1, 0));
  rep(i, N) {
    cin >> v[i].first;
    v[i].second = i;
  }
  vrsort(v);
  rep(i, N) {
    rep(j, i + 1) {
      chmax(dp[i + 1][j + 1], dp[i][j] + v[i].first * abs(v[i].second - j));
      chmax(dp[i + 1][j],
            dp[i][j] + v[i].first * abs(N - 1 - i + j - v[i].second));
    }
  }
  // matoutput(dp);
  print(*max_element(all(dp[N])));
}

Error: TLE

Fixed submission:

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// #include<ext/pb_ds/tag_and_trait.hpp>
// using namespace __gnu_pbds;
// #include<boost/multiprecision/cpp_int.hpp>
// namespace multiprecisioninteger = boost::multiprecision;
// using cint=multiprecisioninteger::cpp_int;
using namespace std;
using ll = long long;
#define double long double
using datas = pair<ll, ll>;
using ddatas = pair<double, double>;
using tdata = pair<ll, datas>;
using vec = vector<ll>;
using mat = vector<vec>;
using pvec = vector<datas>;
using pmat = vector<pvec>;
// using
// llset=tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>;
#define For(i, a, b) for (i = a; i < (ll)b; ++i)
#define bFor(i, b, a) for (i = b, --i; i >= (ll)a; --i)
#define rep(i, N) For(i, 0, N)
#define rep1(i, N) For(i, 1, N)
#define brep(i, N) bFor(i, N, 0)
#define brep1(i, N) bFor(i, N, 1)
#define all(v) (v).begin(), (v).end()
#define allr(v) (v).rbegin(), (v).rend()
#define vsort(v) sort(all(v))
#define vrsort(v) sort(allr(v))
#define endl "\\n"
#define eb emplace_back
#define print(v) cout << v << endl
#define printyes cout << "Yes" << endl
#define printno cout << "No" << endl
#define printYES cout << "YES" << endl
#define printNO cout << "NO" << endl
#define output(v)                                                              \\
  do {                                                                         \\
    bool f = 0;                                                                \\
    for (auto outi : v) {                                                      \\
      cout << (f ? " " : "") << outi;                                          \\
      f = 1;                                                                   \\
    }                                                                          \\
    cout << endl;                                                              \\
  } while (0)
#define matoutput(v)                                                           \\
  do {                                                                         \\
    for (auto outimat : v)                                                     \\
      output(outimat);                                                         \\
  } while (0)
const ll mod = 1000000007;
// const ll mod=998244353;
const ll inf = 1LL << 60;
const double PI = acos(-1);
const double eps = 1e-9;
template <class T> inline bool chmax(T &a, T b) {
  bool x = a < b;
  if (x)
    a = b;
  return x;
}
template <class T> inline bool chmin(T &a, T b) {
  bool x = a > b;
  if (x)
    a = b;
  return x;
}

void startupcpp() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}

double distance(ddatas x, ddatas y) {
  double a = x.first - y.first, b = x.second - y.second;
  return sqrt(a * a + b * b);
}

ll modinv(ll a) {
  ll b = mod, u = 1, v = 0, t;
  while (b) {
    t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  return (u + mod) % mod;
}

ll moddevide(ll a, ll b) { return (a * modinv(b)) % mod; }

vec modncrlistp, modncrlistm;

ll modncr(ll n, ll r) {
  if (n < r)
    return 0;
  ll i, size = modncrlistp.size();
  if (size <= n) {
    modncrlistp.resize(n + 1);
    modncrlistm.resize(n + 1);
    if (!size) {
      modncrlistp[0] = modncrlistm[0] = 1;
      size++;
    }
    For(i, size, n + 1) {
      modncrlistp[i] = modncrlistp[i - 1] * i % mod;
      modncrlistm[i] = modinv(modncrlistp[i]);
    }
  }
  return modncrlistp[n] * modncrlistm[r] % mod * modncrlistm[n - r] % mod;
}

ll modpow(ll a, ll n) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}

ll gcd(ll a, ll b) {
  if (!b)
    return a;
  return (a % b == 0) ? b : gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

ll countdigits(ll n) {
  ll ans = 0;
  while (n) {
    n /= 10;
    ans++;
  }
  return ans;
}

ll sumdigits(ll n) {
  ll ans = 0;
  while (n) {
    ans += n % 10;
    n /= 10;
  }
  return ans;
}
template <typename flow_t, typename cost_t> struct PrimalDual {
  const cost_t INF;

  struct edge {
    int to;
    flow_t cap;
    cost_t cost;
    int rev;
    bool isrev;
  };
  vector<vector<edge>> graph;
  vector<cost_t> potential, min_cost;
  vector<int> prevv, preve;

  PrimalDual(int V) : graph(V), INF(numeric_limits<cost_t>::max()) {}

  void add_edge(int from, int to, flow_t cap, cost_t cost) {
    graph[from].emplace_back(
        (edge){to, cap, cost, (int)graph[to].size(), false});
    graph[to].emplace_back(
        (edge){from, 0, -cost, (int)graph[from].size() - 1, true});
  }

  cost_t min_cost_flow(int s, int t, flow_t f) {
    int V = (int)graph.size();
    cost_t ret = 0;
    using Pi = pair<cost_t, int>;
    priority_queue<Pi, vector<Pi>, greater<Pi>> que;
    potential.assign(V, 0);
    preve.assign(V, -1);
    prevv.assign(V, -1);

    while (f > 0) {
      min_cost.assign(V, INF);
      que.emplace(0, s);
      min_cost[s] = 0;
      while (!que.empty()) {
        Pi p = que.top();
        que.pop();
        if (min_cost[p.second] < p.first)
          continue;
        for (int i = 0; i < graph[p.second].size(); i++) {
          edge &e = graph[p.second][i];
          cost_t nextCost = min_cost[p.second] + e.cost + potential[p.second] -
                            potential[e.to];
          if (e.cap > 0 && min_cost[e.to] > nextCost) {
            min_cost[e.to] = nextCost;
            prevv[e.to] = p.second, preve[e.to] = i;
            que.emplace(min_cost[e.to], e.to);
          }
        }
      }
      if (min_cost[t] == INF)
        return -1;
      for (int v = 0; v < V; v++)
        potential[v] += min_cost[v];
      flow_t addflow = f;
      for (int v = t; v != s; v = prevv[v]) {
        addflow = min(addflow, graph[prevv[v]][preve[v]].cap);
      }
      f -= addflow;
      ret += addflow * potential[t];
      for (int v = t; v != s; v = prevv[v]) {
        edge &e = graph[prevv[v]][preve[v]];
        e.cap -= addflow;
        graph[v][e.rev].cap += addflow;
      }
    }
    return ret;
  }
};

int main() {
  startupcpp();
  // int codeforces;cin>>codeforces;while(codeforces--){
  ll i, j, N, M, x;
  cin >> N;
  PrimalDual<int, ll> fl((N + 1) << 1);
  rep(i, N) {
    cin >> x;
    rep(j, N) { fl.add_edge(i, j + N, 1, -x * abs(i - j)); }
    fl.add_edge(N << 1, i, 1, 0);
    fl.add_edge(i + N, N << 1 | 1, 1, 0);
  }
  print(-fl.min_cost_flow(N << 1, N << 1 | 1, N));
}