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

#include <bits/stdc++.h>
#ifdef __LOCAL
#define DBG(X) cout << #X << " = " << (X) << endl;
#define SAY(X) cout << (X) << endl;
#include <filesystem>
namespace fs = std::filesystem;
#else
#define DBG(X)
#define SAY(X)
#endif

using namespace std;

using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, 1, -1, -1};
const int INT_INF = (int)(2e9);
const ll LL_INF = (ll)(2e18);
static mt19937 _g(time(nullptr));

inline ll randint(ll a, ll b) {
  ll w = (_g() << 31LL) ^ _g();
  return a + w % (b - a + 1);
}
inline void fast_io() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
};
template <typename T, typename S>
inline ostream &operator<<(ostream &os, const pair<T, S> p) {
  cout << "[" << p.first << ";" << p.second << "]";
  return os;
}
template <typename T, typename S>
inline ostream &operator<<(ostream &os, const map<T, S> p) {
  for (auto el : p)
    cout << "[" << el.first << ";" << el.second << "]";
  return os;
}
template <typename T>
inline ostream &operator<<(ostream &os, const vector<T> &v) {
  for (auto el : v)
    cout << el << " ";
  return os;
}
template <typename T> inline vector<T> fetch_vec(int sz) {
  vector<T> ret(sz);
  for (auto &elem : ret)
    cin >> elem;
  return ret;
}

int N;
vector<ll> A;
// priority_queue<pll> pq;
vector<pll> babies;
void input() {
  fast_io();
#ifdef __LOCAL
  fs::path __p = __FILE__;
  fs::path __input, __output;
  __input = __output = __p.parent_path();
  __input += string("/input/") + string(__p.stem()) + string(".txt");
  __output += string("/output/") + string(__p.stem()) + string(".txt");
  freopen(__input.c_str(), "r", stdin);
  freopen(__output.c_str(), "w", stdout);
#endif
  cin >> N;
  for (int i = 0; i < N; i++) {
    ll a;
    cin >> a;
    A.push_back(a);
    // pq.emplace(a,i);
    babies.emplace_back(a, i);
  }
  sort(babies.begin(), babies.end(), greater<pll>());
  DBG(babies)
}

int solve() {
  ll ans = 0;
  vector<vector<ll>> dp(N + 1, vector<ll>(N + 1, 0));
  for (int l = 0; l < N; l++) {
    for (int r = 0; r < N; r++) {
      if (l + r > N)
        continue;
      if (l + r == N) {
        ans = max(ans, dp[l][r]);
        break;
      }
      pll baby = babies[l + r];
      ll baby_a = baby.first;
      int baby_idx = baby.second;
      dp[l + 1][r] = max(dp[l + 1][r], dp[l][r] + baby_a * abs(l - baby_idx));
      dp[l][r + 1] =
          max(dp[l][r + 1], dp[l][r] + baby_a * abs(N - r - 1 - baby_idx));
    }
  }
  cout << ans << endl;

  return 0;
}

ll calScore(vector<ll> a, vector<ll> c) {
  ll ret = 0;
  int n = a.size();
  vector<bool> used(n, false);
  for (int i = 0; i < n; i++) {
    for (int j = n - 1; j >= 0; j--) {
      if (used[j])
        continue;
      if (a[i] == c[j]) {
        ret += a[i] * abs(i - j);
        used[j] = true;
        break;
      }
    }
  }

  return ret;
}

// これはTLEの解法O(N!)
ll test() {
  vector<int> vec;
  ll ans = 0;
  for (int i = 0; i < N; i++)
    vec.push_back(i);

  do {
    vector<ll> ne;
    for (int i = 0; i < N; i++)
      ne.push_back(A[vec[i]]);
    ll d = calScore(A, ne);
    if (d > ans) {
      DBG(d)
      DBG(ne)
    }
    ans = max(ans, d);

  } while (next_permutation(vec.begin(), vec.end()));
  return ans;
}

int main() {
  input();
  solve();
  // cout << test() << endl;
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#ifdef __LOCAL
#define DBG(X) cout << #X << " = " << (X) << endl;
#define SAY(X) cout << (X) << endl;
#include <filesystem>
namespace fs = std::filesystem;
#else
#define DBG(X)
#define SAY(X)
#endif

using namespace std;

using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, 1, -1, -1};
const int INT_INF = (int)(2e9);
const ll LL_INF = (ll)(2e18);
static mt19937 _g(time(nullptr));

inline ll randint(ll a, ll b) {
  ll w = (_g() << 31LL) ^ _g();
  return a + w % (b - a + 1);
}
inline void fast_io() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
};
template <typename T, typename S>
inline ostream &operator<<(ostream &os, const pair<T, S> p) {
  cout << "[" << p.first << ";" << p.second << "]";
  return os;
}
template <typename T, typename S>
inline ostream &operator<<(ostream &os, const map<T, S> p) {
  for (auto el : p)
    cout << "[" << el.first << ";" << el.second << "]";
  return os;
}
template <typename T>
inline ostream &operator<<(ostream &os, const vector<T> &v) {
  for (auto el : v)
    cout << el << " ";
  return os;
}
template <typename T> inline vector<T> fetch_vec(int sz) {
  vector<T> ret(sz);
  for (auto &elem : ret)
    cin >> elem;
  return ret;
}

int N;
vector<ll> A;
priority_queue<pll> pq;
void input() {
  fast_io();
#ifdef __LOCAL
  fs::path __p = __FILE__;
  fs::path __input, __output;
  __input = __output = __p.parent_path();
  __input += string("/input/") + string(__p.stem()) + string(".txt");
  __output += string("/output/") + string(__p.stem()) + string(".txt");
  freopen(__input.c_str(), "r", stdin);
  freopen(__output.c_str(), "w", stdout);
#endif
  cin >> N;
  for (int i = 0; i < N; i++) {
    ll a;
    cin >> a;
    A.push_back(a);
    pq.emplace(a, i);
  }
}

int solve() {
  ll ans = 0;
  vector<bool> used(N, false);
  vector<ll> changed(N, 0);
  while (!pq.empty()) {
    ll a;
    ll idx;
    tie(a, idx) = pq.top();
    pq.pop();
    ll le = 0;
    ll ri = N - 1;
    while (used[le])
      le++;
    while (used[ri])
      ri--;
    if (abs(ri - idx) > abs(idx - le)) {
      changed[ri] = a;
      ans += a * abs(ri - idx);
      used[ri] = true;
    } else {
      changed[le] = a;
      ans += a * abs(le - idx);
      used[le] = true;
    }
  }
  DBG(changed)
  ll ans2 = 0;
  DBG(ans)
  vector<bool> seen(N, false);
  for (int i = 0; i < N; i++) {
    for (int j = N - 1; j >= 0; j--) {
      if (seen[j])
        continue;
      if (A[i] == changed[j]) {
        ans2 += A[i] * abs(i - j);
        seen[j] = true;
        break;
      }
    }
  }

  cout << max(ans, ans2) << endl;
  return 0;
}

ll calScore(vector<ll> a, vector<ll> c) {
  ll ret = 0;
  int n = a.size();
  vector<bool> used(n, false);
  for (int i = 0; i < n; i++) {
    for (int j = n - 1; j >= 0; j--) {
      if (used[j])
        continue;
      if (a[i] == c[j]) {
        ret += a[i] * abs(i - j);
        used[j] = true;
        break;
      }
    }
  }

  return ret;
}

ll test() {
  vector<int> vec;
  ll ans = 0;
  for (int i = 0; i < N; i++)
    vec.push_back(i);

  do {
    vector<ll> ne;
    for (int i = 0; i < N; i++)
      ne.push_back(A[vec[i]]);
    ll d = calScore(A, ne);
    ans = max(ans, d);
    // if(d>=102){
    //     DBG(ne)
    //     DBG(d)
    // }

  } while (next_permutation(vec.begin(), vec.end()));
  return ans;
}

int main() {
  input();
  // solve();
  cout << test() << endl;
  return 0;
}