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

#include <algorithm>
#include <cmath>
#include <cstring>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define per(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define pb push_back
#define mp make_pair
#define bg begin()
#define en end()
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define sz(v) (int)(v).size()

using namespace std;

typedef long long ll;
typedef long double ld;

using P = pair<int, int>;
template <typename T> struct Edge {
  int u, v;
  T cost;
  Edge(int u, int v, T c) : u(u), v(v), cost(c) {}
  bool operator<(const Edge &e) const { return cost < e.cost; }
};

static const long long mod = 998244353;
static const long long LINF = (ll)(1e18 + 99);
static const int INF = 1e9 + 99;

template <int mod> struct ModInt {
  int x;
  ModInt() : x(0) {}
  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }
  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }
  ModInt operator-() const { return ModInt(-x); }
  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
  bool operator==(const ModInt &p) const { return x == p.x; }
  bool operator!=(const ModInt &p) const { return x != p.x; }
  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }
  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1)
        ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }
  friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; }
  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt<mod>(t);
    return (is);
  }
  static int get_mod() { return mod; }
};
using mint = ModInt<mod>;

ll ans;
mint dp[200005];
mint S[200005];
vector<int> L, R;

int main(void) {
  int n, k;
  cin >> n >> k;
  vector<int> v;
  rep(i, 0, k) {
    int l, r;
    cin >> l >> r;
    L.pb(l);
    R.pb(r);
  }

  dp[1] = 1;
  S[1] = 1;
  rep(i, 2, n + 1) {
    rep(j, 0, k) {
      int l = i - R[j], r = i - L[j];
      if (r < 1)
        continue;
      mint x = S[r] - S[max(0, l - 1)];
      dp[i] += x;
    }
    S[i] += S[i - 1] + dp[i];
  }

  cout << dp[n] << endl;
  return 0;
}


Error: TLE

Fixed submission:

#include <algorithm>
#include <cmath>
#include <cstring>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define per(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define pb push_back
#define mp make_pair
#define bg begin()
#define en end()
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define sz(v) (int)(v).size()

using namespace std;

typedef long long ll;
typedef long double ld;

using P = pair<int, int>;
template <typename T> struct Edge {
  int u, v;
  T cost;
  Edge(int u, int v, T c) : u(u), v(v), cost(c) {}
  bool operator<(const Edge &e) const { return cost < e.cost; }
};

static const long long mod = 998244353;
static const long long LINF = (ll)(1e18 + 99);
static const int INF = 1e9 + 99;

template <int mod> struct ModInt {
  int x;
  ModInt() : x(0) {}
  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }
  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }
  ModInt operator-() const { return ModInt(-x); }
  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
  bool operator==(const ModInt &p) const { return x == p.x; }
  bool operator!=(const ModInt &p) const { return x != p.x; }
  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }
  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1)
        ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }
  friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; }
  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt<mod>(t);
    return (is);
  }
  static int get_mod() { return mod; }
};
using mint = ModInt<mod>;

ll ans;
mint dp[200005];

int main(void) {
  int n, k;
  cin >> n >> k;
  vector<int> v;
  rep(i, 0, k) {
    int L, R;
    cin >> L >> R;
    rep(j, L, R + 1) v.pb(j);
  }
  sort(all(v));

  dp[1] = 1;
  rep(i, 2, n + 1) {
    rep(j, 0, sz(v)) {
      if (i - v[j] >= 0)
        dp[i] += dp[i - v[j]];
    }
  }

  cout << dp[n] << endl;
  return 0;
}