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

#include <algorithm>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define range(a) a.begin(), a.end()
#define endl "\\n"
#define Yes() cout << "Yes" << endl
#define No() cout << "No" << endl
#define MP make_pair
using Graph = vector<vector<int>>;
const ll mod = 998244353;
const long long INF = 1LL << 60;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
void chmin(long long &a, long long b) {
  if (a > b)
    a = b;
}
void chmax(long long &a, long long b) {
  if (a < b)
    a = b;
}

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
// const int mod = 1000000007;
// const int mod = 998244353;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  mint dp[200005] = {};
  mint dpsum[200005] = {};
  dp[0] = 1;
  dpsum[0] = 1;
  int N, K;
  cin >> N >> K;
  vector<pair<int, int>> data;
  while (K--) {
    int L, R;
    cin >> L >> R;
    data.push_back(MP(L, R));
  }

  FOR(i, 1, N) {
    FOR(j, 0, data.size()) {
      int r = i - data.at(j).first, l = i - data.at(j).second - 1;
      if (r < 0)
        continue;
      if (l < 0)
        dp[i] += dpsum[r];
      else
        dp[i] += dpsum[r] - dpsum[l];
    }
    dpsum[i] = dpsum[i - 1] + dp[i];
  }

  // FOR(i,0,N)	cout << i << " " << dp[i] << endl;
  cout << dp[N - 1] << endl;

  return 0;
}


Error: TLE

Fixed submission:

#include <algorithm>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define range(a) a.begin(), a.end()
#define endl "\\n"
#define Yes() cout << "Yes" << endl
#define No() cout << "No" << endl
#define MP make_pair
using Graph = vector<vector<int>>;
const ll mod = 998244353;
const long long INF = 1LL << 60;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
void chmin(long long &a, long long b) {
  if (a > b)
    a = b;
}
void chmax(long long &a, long long b) {
  if (a < b)
    a = b;
}

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
// const int mod = 1000000007;
// const int mod = 998244353;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  mint dp[200005] = {};
  dp[0] = 1;
  int N, K;
  cin >> N >> K;
  vector<pair<int, int>> data;
  while (K--) {
    int L, R;
    cin >> L >> R;
    data.push_back(MP(L, R));
  }

  FOR(i, 0, N) {
    FOR(j, 0, data.size()) {
      int f = data.at(j).first, s = data.at(j).second;
      FOR(k, f, s + 1) {
        if (i + k <= N) {
          dp[i + k] += dp[i];
        }
      }
    }
  }

  cout << dp[N - 1] << endl;

  return 0;
}