Problem p02603 (C++) — buggy submission, verdict: Time Limit Exceeded

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

#define IOS                                                                    \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0)
#define rep(pp, nn) for (int ii = pp; ii < nn; ++ii)
#define vi vector<int>
#define vll vector<ll>
#define vs vector<string>

void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\\'' << x << '\\''; }
void __print(const char *x) { cerr << '\\"' << x << '\\"'; }
void __print(const string &x) { cerr << '\\"' << x << '\\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }

string int_to_string(int x) {
  stringstream ss;
  ss << x;
  string ni = ss.str();
  return ni;
}
int string_to_int(string x) {
  int n;
  stringstream s(x);
  s >> n;
  return n;
}

int64_t power_mod(ll a, ll b, ll mo) {
  ll ans = 1;
  while (b) {
    if (b & 1) {
      ans = (ans % mo * a % mo) % mo;
    }
    a = (a % mo * a % mo) % mo;
    b /= 2;
  }
  return ans;
}
int64_t POW(ll a, ll b) {
  ll ans = 1;
  while (b) {
    if (b & 1) {
      ans = ans * a;
    }
    a = a * a;
    b /= 2;
  }
  return ans;
}

vector<int64_t> INVERSE(int64_t nn, int64_t mo) {
  vector<int64_t> inv(nn + 1);
  vector<int64_t> mul(nn + 1);
  inv[0] = 1;
  inv[1] = 1;
  for (ll i = 2; i <= nn; ++i) {
    inv[i] = (mo - (mo / i) * inv[mo % i] % mo) % mo;
  }
  mul[0] = 1;
  for (int i = 1; i <= nn; ++i) {
    mul[i] = (mul[i - 1] * inv[i]) % mo;
  }
  return mul;
}

template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}

#ifndef ONLINE_JUDGE
#define debug(x...)                                                            \\
  cerr << "[" << #x << "] = [";                                                \\
  _print(x)
#else
#define debug(x...)
#endif

int main() {
  int n;
  cin >> n;
  vector<int64_t> a(n);
  int64_t ans = 1000;
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    // if (i) {
    // if (v[i] > v[i - 1]) {
    // int64_t x = ans / v[i - 1];
    // ans = ans % v[i - 1];
    // ans += x * v[i];
    //}
    //}
  }
  for (int i = 0; i + 1 < n; ++i) {
    int64_t stocks = ans / a[i];
    ans += stocks * (max(a[i + 1] - a[i], (int64_t)0));
  }
  cout << ans;
}


Error: TLE

Fixed submission:

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

#define IOS                                                                    \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0)
#define rep(pp, nn) for (int ii = pp; ii < nn; ++ii)
#define vi vector<int>
#define vll vector<ll>
#define vs vector<string>

void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\\'' << x << '\\''; }
void __print(const char *x) { cerr << '\\"' << x << '\\"'; }
void __print(const string &x) { cerr << '\\"' << x << '\\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }

string int_to_string(int x) {
  stringstream ss;
  ss << x;
  string ni = ss.str();
  return ni;
}
int string_to_int(string x) {
  int n;
  stringstream s(x);
  s >> n;
  return n;
}

int64_t power_mod(ll a, ll b, ll mo) {
  ll ans = 1;
  while (b) {
    if (b & 1) {
      ans = (ans % mo * a % mo) % mo;
    }
    a = (a % mo * a % mo) % mo;
    b /= 2;
  }
  return ans;
}
int64_t POW(ll a, ll b) {
  ll ans = 1;
  while (b) {
    if (b & 1) {
      ans = ans * a;
    }
    a = a * a;
    b /= 2;
  }
  return ans;
}

vector<int64_t> INVERSE(int64_t nn, int64_t mo) {
  vector<int64_t> inv(nn + 1);
  vector<int64_t> mul(nn + 1);
  inv[0] = 1;
  inv[1] = 1;
  for (ll i = 2; i <= nn; ++i) {
    inv[i] = (mo - (mo / i) * inv[mo % i] % mo) % mo;
  }
  mul[0] = 1;
  for (int i = 1; i <= nn; ++i) {
    mul[i] = (mul[i - 1] * inv[i]) % mo;
  }
  return mul;
}

template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}

#ifndef ONLINE_JUDGE
#define debug(x...)                                                            \\
  cerr << "[" << #x << "] = [";                                                \\
  _print(x)
#else
#define debug(x...)
#endif

vector<int> v(81);
int n;
int ans = 1000;
map<vector<int>, int> m;

void rec(int index, int val, int stock, int last) {
  if (index == n) {
    ans = max(ans, val);
    return;
  }
  vector<int> a = {val, stock, index};
  auto it = m.find(a);
  if (it != m.end()) {
    return;
  }
  if (v[index] > last) {
    int x = stock;
    int p = 1;
    while (x) {
      rec(index + 1, val + p * v[index], x - 1, v[index]);
      p++;
      x--;
    }
  } else {
    int p = 1;
    int price = v[index];
    while (val - price >= 0) {
      rec(index + 1, val - price, stock + p, v[index]);
      price += v[index];
      p++;
    }
  }
  rec(index + 1, val, stock, v[index]);
  m[a] = 1;
}

int main() {
  cin >> n;
  // memset(dp,-1,sizeof(dp));
  for (int i = 0; i < n; ++i) {
    cin >> v[i];
  }
  rec(0, 1000, 0, 1000);
  cout << ans;
}