Problem p02549 (C++) — buggy submission, verdict: Time Limit Exceeded

#define LOCAL

#include <bits/stdc++.h>

using namespace std;

#define IOS                                                                    \\
  ios::sync_with_stdio(false);                                                 \\
  cin.tie(0)
#define all(x) x.begin(), x.end()
#define ff first
#define ss second
#define LLINF 0x3f3f3f3f3f3f3f3f
#define INF 0x3f3f3f3f

#define LOCAL

// Copied from Gennady-Korotkevich's template

template <typename A, typename B> string to_string(pair<A, B> p);

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string &s) { return '"' + s + '"'; }

string to_string(const char *s) { return to_string((string)s); }

string to_string(bool b) { return (b ? "true" : "false"); }

string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}\\n";
  return res;
}

template <size_t N> string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}

template <typename A> string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}\\n";
  return res;
}

template <typename A, typename B> string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " +
         to_string(get<2>(p)) + ")";
}

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " +
         to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

template <typename A, typename B, typename C, typename D, typename E>
string to_string(tuple<A, B, C, D, E> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " +
         to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + "," +
         to_string(get<4>(p)) + ")";
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail> void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}

#ifdef LOCAL
#define debug(...)                                                             \\
  cerr << "\\n[" << #__VA_ARGS__ << "]:\\n", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

// End of Gennady-Korotkevich's template

using llong = long long;
using PII = pair<int, int>;

const llong MOD = 998244353LL;
const double PI = acos(-1);

llong add(llong a, llong b) {
  a += b;
  if (a >= MOD)
    return a - MOD;
  return a;
}

int main() {
  IOS;
  int n, k;
  cin >> n >> k;
  vector<PII> jump(k);
  for (int i = 0; i < k; i++) {
    int l, r;
    cin >> l >> r;
    jump[i] = {l, r};
  }
  sort(jump.begin(), jump.end());
  vector<llong> dp(n + 1), realAns(n + 1);
  dp[0] = 1;
  for (int i = 0; i < n; i++) {
    if (i == 0)
      realAns[i] = dp[i];
    else {
      realAns[i] = realAns[i - 1] + dp[i];
      realAns[i] %= MOD;
    }
    for (int j = 0; j < jump.size(); j++) {
      if (i + jump[j].ff >= n)
        break;
      dp[i + jump[j].ff] += realAns[i];
      dp[i + jump[j].ff] %= MOD;
      dp[min(n, i + jump[j].ss + 1)] -= realAns[i];
      dp[min(n, i + jump[j].ss + 1)] %= MOD;
      dp[min(n, i + jump[j].ss + 1)] += MOD;
      dp[min(n, i + jump[j].ss + 1)] %= MOD;
    }
  }
  cout << dp[n - 1];
}

Error: TLE

Fixed submission:

#define LOCAL

#include <bits/stdc++.h>

using namespace std;

#define IOS                                                                    \\
  ios::sync_with_stdio(false);                                                 \\
  cin.tie(0)
#define all(x) x.begin(), x.end()
#define ff first
#define ss second
#define LLINF 0x3f3f3f3f3f3f3f3f
#define INF 0x3f3f3f3f

using llong = long long;
using PII = pair<int, int>;

const llong MOD = 998244353LL;
const double PI = acos(-1);

llong add(llong a, llong b) {
  a += b;
  if (a >= MOD)
    return a - MOD;
  return a;
}

int main() {
  IOS;
  int n, k;
  cin >> n >> k;
  vector<llong> jump;
  for (int i = 0; i < k; i++) {
    int l, r;
    cin >> l >> r;
    for (int j = l; j <= r; j++) {
      jump.push_back(j);
    }
  }
  sort(jump.begin(), jump.end());
  vector<llong> dp(n);
  dp[0] = 1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < jump.size(); j++) {
      if (i + jump[j] >= n)
        break;
      dp[i + jump[j]] = add(dp[i + jump[j]], dp[i]);
    }
  }
  cout << dp[n - 1];
}