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

#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <algorithm>
#include <cassert>
#include <cfloat>
#include <complex>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define repLRE(i, l, r) for (ll i = (l); i <= (r); ++i)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define Lower_bound(v, x)                                                      \\
  distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x)                                                      \\
  distance(v.begin(), upper_bound(v.begin(), v.end(), x))

using ll = long long;
using ull = unsigned long long;
using P = pair<ll, ll>;
using T = tuple<ll, ll, ll>;
using vll = vector<ll>;
using vP = vector<P>;
using vT = vector<T>;
using vvll = vector<vector<ll>>;
using vvP = vector<vector<P>>;
using dqll = deque<ll>;

ll dx[9] = {-1, 1, 0, 0, -1, -1, 1, 1, 0};
ll dy[9] = {0, 0, -1, 1, -1, 1, -1, 1, 0};

/* Macros reg. ends here */

const ll INF = 1LL << 50;

int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cout << fixed << setprecision(15);

  string s;
  cin >> s;
  ll n = s.size();

  vvll dp(2, vll(2019, 0));
  ll ans = 0;
  rep(i, n) {
    ll now = s[i] - '0';
    ans += dp[i % 2][2019 - now];
    rep(j, 2019) {
      dp[(i + 1) % 2][10 * (now + j) % 2019] = dp[i % 2][j];
      // if (dp[i][j] > 0) printf("add %lld at %lld\\n", dp[i][j], j);
    }
    dp[(i + 1) % 2][10 * now] += 1;
    // cout << "i=" << i << endl;
    // rep(kk, 2019) cout << kk << ":"<< dp[i+1][kk] << endl;
  }
  cout << ans << endl;

  return 0;
}


Error: TLE

Fixed submission:

#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <algorithm>
#include <cassert>
#include <cfloat>
#include <complex>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define repLRE(i, l, r) for (ll i = (l); i <= (r); ++i)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define Lower_bound(v, x)                                                      \\
  distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x)                                                      \\
  distance(v.begin(), upper_bound(v.begin(), v.end(), x))

using ll = long long;
using ull = unsigned long long;
using P = pair<ll, ll>;
using T = tuple<ll, ll, ll>;
using vll = vector<ll>;
using vP = vector<P>;
using vT = vector<T>;
using vvll = vector<vector<ll>>;
using vvP = vector<vector<P>>;
using dqll = deque<ll>;

ll dx[9] = {-1, 1, 0, 0, -1, -1, 1, 1, 0};
ll dy[9] = {0, 0, -1, 1, -1, 1, -1, 1, 0};

/* Macros reg. ends here */

const ll INF = 1LL << 50;

int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cout << fixed << setprecision(15);

  string s;
  cin >> s;
  ll n = s.size();

  vvll dp(n + 1, vll(2019, 0));
  ll ans = 0;
  rep(i, n) {
    ll now = s[i] - '0';
    ans += dp[i][2019 - now];
    rep(j, 2019) {
      dp[i + 1][10 * (now + j) % 2019] = dp[i][j];
      // if (dp[i][j] > 0) printf("add %lld at %lld\\n", dp[i][j], j);
    }
    dp[i + 1][10 * now] += 1;
    // cout << "i=" << i << endl;
    // rep(kk, 2019) cout << kk << ":"<< dp[i+1][kk] << endl;
  }
  cout << ans << endl;

  return 0;
}