Problem p02702 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<long long> vll;
#define left(x) (x << 1)
#define right(x) (x << 1) + 1
#define mid(l, r) ((l + r) >> 1)
#define mp make_pair
#define pb push_back
#define all(a) a.begin(), a.end()
#define debug(x)                                                               \\
  { cerr << #x << " = " << x << "\\n"; }
#define debug2(x, y)                                                           \\
  { cerr << #x << " = " << x << ", " << #y << " = " << y << "\\n"; }
#define debug3(x, y, z)                                                        \\
  {                                                                            \\
    cerr << #x << " = " << x << ", " << #y << " = " << y << ", " << #z         \\
         << " = " << z << "\\n";                                                \\
  }
#define debug4(x, y, z, w)                                                     \\
  {                                                                            \\
    cerr << #x << " = " << x << ", " << #y << " = " << y << ", " << #z         \\
         << " = " << z << ", " << #w << " = " << w << "\\n";                    \\
  }
#define ss second
#define ff first
#define m0(x) memset(x, 0, sizeof(x))

template <typename T> T min_(T a, T b) { return a > b ? b : a; }
template <typename T, typename... Ts> T min_(T first, Ts... last) {
  return min_(first, min_(last...));
}
template <typename T> T max_(T a, T b) { return a > b ? a : b; }
template <typename T, typename... Ts> T max_(T first, Ts... last) {
  return max_(first, min_(last...));
}

template <class T, class S>
std::ostream &operator<<(std::ostream &os, const std::pair<T, S> &t) {
  os << "(" << t.first << ", " << t.second << ")";
  return os;
}
template <typename T> ostream &operator<<(ostream &out, const vector<T> &v) {
  out << "[";
  size_t last = v.size() - 1;
  for (size_t i = 0; i < v.size(); ++i) {
    out << v[i];
    if (i != last)
      out << ", ";
  }
  out << "]";
  return out;
}
const int mod = 1e9 + 7;

ll pwr(ll base, ll p) {
  ll ans = 1;
  while (p) {
    if (p & 1)
      ans = (ans * base) % mod;
    base = (base * base) % mod;
    p /= 2;
  }
  return ans;
}
ll gcd(ll a, ll b) { return b == 0 ? a : gcd(b, a % b); }
ll lcm(ll a, ll b) { return a * (b / gcd(a, b)); }

const long double PI = (long double)(3.1415926535897932384626433832795);
const ll mx_ll = numeric_limits<ll>::max();
const int mx_int = numeric_limits<int>::max();

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  string s;
  cin >> s;
  int n = s.size();
  ll fans = 0;
  vector<ll> curr(2020);
  curr[s[0] - '0'] = 1;
  for (int i = 1; i < n; ++i) {
    vector<ll> tmp(2020);
    tmp[s[i] - '0'] = 1;
    for (int r = 0; r <= 2019; ++r) {
      if (!curr[r])
        continue;
      int nr = (10 * r + s[i] - '0') % 2019;
      if (nr == 0)
        fans += curr[r];
      tmp[nr] += curr[r];
    }
    curr.clear();
    curr = tmp;
  }
  cout << fans << endl;

  // for(int i = 0; i < n; ++i) {
  //     int rem = 0;
  //     ll pf = 0;
  //     for(int j = i; j < n; ++j) {
  //         rem = (10*rem + s[j]-'0') % 2019;
  //         if(vis[j][rem]) break;
  //         vis[j][rem] = 1;
  //         if(rem == 0) pf += 1;
  //     }
  //     fans += (pf * ( pf + 1)) / 2;
  // }
  // cout << fans << endl;

  return 0;
}


Error: TLE

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<long long> vll;
#define left(x) (x << 1)
#define right(x) (x << 1) + 1
#define mid(l, r) ((l + r) >> 1)
#define mp make_pair
#define pb push_back
#define all(a) a.begin(), a.end()
#define debug(x)                                                               \\
  { cerr << #x << " = " << x << "\\n"; }
#define debug2(x, y)                                                           \\
  { cerr << #x << " = " << x << ", " << #y << " = " << y << "\\n"; }
#define debug3(x, y, z)                                                        \\
  {                                                                            \\
    cerr << #x << " = " << x << ", " << #y << " = " << y << ", " << #z         \\
         << " = " << z << "\\n";                                                \\
  }
#define debug4(x, y, z, w)                                                     \\
  {                                                                            \\
    cerr << #x << " = " << x << ", " << #y << " = " << y << ", " << #z         \\
         << " = " << z << ", " << #w << " = " << w << "\\n";                    \\
  }
#define ss second
#define ff first
#define m0(x) memset(x, 0, sizeof(x))

template <typename T> T min_(T a, T b) { return a > b ? b : a; }
template <typename T, typename... Ts> T min_(T first, Ts... last) {
  return min_(first, min_(last...));
}
template <typename T> T max_(T a, T b) { return a > b ? a : b; }
template <typename T, typename... Ts> T max_(T first, Ts... last) {
  return max_(first, min_(last...));
}

template <class T, class S>
std::ostream &operator<<(std::ostream &os, const std::pair<T, S> &t) {
  os << "(" << t.first << ", " << t.second << ")";
  return os;
}
template <typename T> ostream &operator<<(ostream &out, const vector<T> &v) {
  out << "[";
  size_t last = v.size() - 1;
  for (size_t i = 0; i < v.size(); ++i) {
    out << v[i];
    if (i != last)
      out << ", ";
  }
  out << "]";
  return out;
}
const int mod = 1e9 + 7;

ll pwr(ll base, ll p) {
  ll ans = 1;
  while (p) {
    if (p & 1)
      ans = (ans * base) % mod;
    base = (base * base) % mod;
    p /= 2;
  }
  return ans;
}
ll gcd(ll a, ll b) { return b == 0 ? a : gcd(b, a % b); }
ll lcm(ll a, ll b) { return a * (b / gcd(a, b)); }

const long double PI = (long double)(3.1415926535897932384626433832795);
const ll mx_ll = numeric_limits<ll>::max();
const int mx_int = numeric_limits<int>::max();

const int maxn = 2e5 + 7;
unordered_map<int, int> vis[maxn];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  string s;
  cin >> s;
  int n = s.size();
  ll fans = 0;
  map<int, int> cnt;
  cnt[s[0] - '0'] = 1;
  for (int i = 0; i < n; ++i) {
    map<int, int> tmp;
    tmp[s[i] - '0'] = 1;
    for (auto r : cnt) {
      int nr = (10 * r.ff + s[i] - '0') % 2019;
      if (nr == 0)
        fans += r.ss;
      tmp[nr] = r.ss;
    }
    cnt.clear();
    cnt.insert(tmp.begin(), tmp.end());
  }
  cout << fans << endl;

  // for(int i = 0; i < n; ++i) {
  //     int rem = 0;
  //     ll pf = 0;
  //     for(int j = i; j < n; ++j) {
  //         rem = (10*rem + s[j]-'0') % 2019;
  //         if(vis[j][rem]) break;
  //         vis[j][rem] = 1;
  //         if(rem == 0) pf += 1;
  //     }
  //     fans += (pf * ( pf + 1)) / 2;
  // }
  // cout << fans << endl;

  return 0;
}