Problem p02549 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
#define repi(i, a, b) for (ll i = (a); i < (b); ++i)
#define rep(i, a) repi(i, 0, a)
#define repdi(i, a, b) for (ll i = (a)-1; i >= (b); --i)
#define repd(i, a) repdi(i, a, 0)
#define itr(it, a) for (auto it = (a).begin(); it != (a).end(); ++it)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define endl '\\n'
#define debug(x) std::cerr << #x << " = " << (x) << endl;

using ll = long long;
using P = std::pair<ll, ll>;

using namespace std;

constexpr ll INF = 1ll << 60;

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}

template <class S, class T>
std::ostream &operator<<(std::ostream &out, const std::pair<S, T> &a) {
  std::cout << '(' << a.first << ", " << a.second << ')';
  return out;
}

template <class T>
std::ostream &operator<<(std::ostream &out, const std::vector<T> &a) {
  std::cout << '[';
  rep(i, a.size()) {
    std::cout << a[i];
    if (i != a.size() - 1)
      std::cout << ", ";
  }
  std::cout << ']';
  return out;
}

const ll 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 {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= 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 {
    mint res(*this);
    return res /= a;
  }

  bool operator==(const mint a) const { return this->x == a.x; }
};

template <typename T, typename E> struct SegmentTree {
  using F = function<T(T, T)>;
  using G = function<T(T, E)>;
  using H = function<E(E, E)>;
  int n, height;
  F f;
  G g;
  H h;
  T ti;
  E ei;
  vector<T> dat;
  vector<E> laz;
  SegmentTree(F f, G g, H h, T ti, E ei) : f(f), g(g), h(h), ti(ti), ei(ei) {}

  void init(int n_) {
    n = 1;
    height = 0;
    while (n < n_)
      n <<= 1, height++;
    dat.assign(2 * n, ti);
    laz.assign(2 * n, ei);
  }

  void build(const vector<T> &v) {
    int n_ = v.size();
    init(n_);
    for (int i = 0; i < n_; i++)
      dat[n + i] = v[i];
    for (int i = n - 1; i; i--)
      dat[i] = f(dat[(i << 1) | 0], dat[(i << 1) | 1]);
  }

  inline T reflect(int k) { return laz[k] == ei ? dat[k] : g(dat[k], laz[k]); }

  inline void propagate(int k) {
    if (laz[k] == ei)
      return;
    laz[(k << 1) | 0] = h(laz[(k << 1) | 0], laz[k]);
    laz[(k << 1) | 1] = h(laz[(k << 1) | 1], laz[k]);
    dat[k] = reflect(k);
    laz[k] = ei;
  }

  inline void thrust(int k) {
    for (int i = height; i; i--)
      propagate(k >> i);
  }

  inline void recalc(int k) {
    while (k >>= 1)
      dat[k] = f(reflect((k << 1) | 0), reflect((k << 1) | 1));
  }

  void update(int a, int b, E x) {
    if (a >= b)
      return;
    thrust(a += n);
    thrust(b += n - 1);
    for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
      if (l & 1)
        laz[l] = h(laz[l], x), l++;
      if (r & 1)
        --r, laz[r] = h(laz[r], x);
    }
    recalc(a);
    recalc(b);
  }

  void set_val(int a, T x) {
    thrust(a += n);
    dat[a] = x;
    laz[a] = ei;
    recalc(a);
  }

  T query(int a, int b) {
    if (a >= b)
      return ti;
    thrust(a += n);
    thrust(b += n - 1);
    T vl = ti, vr = ti;
    for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
      if (l & 1)
        vl = f(vl, reflect(l++));
      if (r & 1)
        vr = f(reflect(--r), vr);
    }
    return f(vl, vr);
  }

  template <typename C>
  int find(int st, C &check, T &acc, int k, int l, int r) {
    if (l + 1 == r) {
      acc = f(acc, reflect(k));
      return check(acc) ? k - n : -1;
    }
    propagate(k);
    int m = (l + r) >> 1;
    if (m <= st)
      return find(st, check, acc, (k << 1) | 1, m, r);
    if (st <= l && !check(f(acc, dat[k]))) {
      acc = f(acc, dat[k]);
      return -1;
    }
    int vl = find(st, check, acc, (k << 1) | 0, l, m);
    if (~vl)
      return vl;
    return find(st, check, acc, (k << 1) | 1, m, r);
  }

  template <typename C> int find(int st, C &check) {
    T acc = ti;
    return find(st, check, acc, 1, 0, n);
  }
};

struct combination {
  std::vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

ll N, K;
ll L[200010], R[200010];
mint dp[200010], S[200010];

int main() {
  std::cin >> N >> K;

  rep(i, K) std::cin >> L[i] >> R[i], ++R[i];

  auto madd = [&](mint a, mint b) { return a + b; };

  SegmentTree<mint, mint> seg(madd, madd, madd, 0, 0);

  seg.init(N + 10);
  seg.set_val(0, 1);

  rep(i, N - 1) {
    mint x = seg.query(i, i + 1);

    rep(j, K) {
      if (i + L[j] >= N)
        continue;

      seg.update(i + L[j], std::min(N, i + R[j]), x);
    }
  }

  mint ans = seg.query(N - 1, N);

  std::cout << ans.x << endl;

  return 0;
}

Error: 0

Fixed submission:

#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
#define repi(i, a, b) for (ll i = (a); i < (b); ++i)
#define rep(i, a) repi(i, 0, a)
#define repdi(i, a, b) for (ll i = (a)-1; i >= (b); --i)
#define repd(i, a) repdi(i, a, 0)
#define itr(it, a) for (auto it = (a).begin(); it != (a).end(); ++it)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define endl '\\n'
#define debug(x) std::cerr << #x << " = " << (x) << endl;

using ll = long long;
using P = std::pair<ll, ll>;

using namespace std;

constexpr ll INF = 1ll << 60;

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}

template <class S, class T>
std::ostream &operator<<(std::ostream &out, const std::pair<S, T> &a) {
  std::cout << '(' << a.first << ", " << a.second << ')';
  return out;
}

template <class T>
std::ostream &operator<<(std::ostream &out, const std::vector<T> &a) {
  std::cout << '[';
  rep(i, a.size()) {
    std::cout << a[i];
    if (i != a.size() - 1)
      std::cout << ", ";
  }
  std::cout << ']';
  return out;
}

const ll 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 {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= 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 {
    mint res(*this);
    return res /= a;
  }

  bool operator==(const mint a) const { return this->x == a.x; }
};

template <typename T, typename E> struct SegmentTree {
  using F = function<T(T, T)>;
  using G = function<T(T, E)>;
  using H = function<E(E, E)>;
  int n, height;
  F f;
  G g;
  H h;
  T ti;
  E ei;
  vector<T> dat;
  vector<E> laz;
  SegmentTree(F f, G g, H h, T ti, E ei) : f(f), g(g), h(h), ti(ti), ei(ei) {}

  void init(int n_) {
    n = 1;
    height = 0;
    while (n < n_)
      n <<= 1, height++;
    dat.assign(2 * n, ti);
    laz.assign(2 * n, ei);
  }

  void build(const vector<T> &v) {
    int n_ = v.size();
    init(n_);
    for (int i = 0; i < n_; i++)
      dat[n + i] = v[i];
    for (int i = n - 1; i; i--)
      dat[i] = f(dat[(i << 1) | 0], dat[(i << 1) | 1]);
  }

  inline T reflect(int k) { return laz[k] == ei ? dat[k] : g(dat[k], laz[k]); }

  inline void propagate(int k) {
    if (laz[k] == ei)
      return;
    laz[(k << 1) | 0] = h(laz[(k << 1) | 0], laz[k]);
    laz[(k << 1) | 1] = h(laz[(k << 1) | 1], laz[k]);
    dat[k] = reflect(k);
    laz[k] = ei;
  }

  inline void thrust(int k) {
    for (int i = height; i; i--)
      propagate(k >> i);
  }

  inline void recalc(int k) {
    while (k >>= 1)
      dat[k] = f(reflect((k << 1) | 0), reflect((k << 1) | 1));
  }

  void update(int a, int b, E x) {
    if (a >= b)
      return;
    thrust(a += n);
    thrust(b += n - 1);
    for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
      if (l & 1)
        laz[l] = h(laz[l], x), l++;
      if (r & 1)
        --r, laz[r] = h(laz[r], x);
    }
    recalc(a);
    recalc(b);
  }

  void set_val(int a, T x) {
    thrust(a += n);
    dat[a] = x;
    laz[a] = ei;
    recalc(a);
  }

  T query(int a, int b) {
    if (a >= b)
      return ti;
    thrust(a += n);
    thrust(b += n - 1);
    T vl = ti, vr = ti;
    for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
      if (l & 1)
        vl = f(vl, reflect(l++));
      if (r & 1)
        vr = f(reflect(--r), vr);
    }
    return f(vl, vr);
  }

  template <typename C>
  int find(int st, C &check, T &acc, int k, int l, int r) {
    if (l + 1 == r) {
      acc = f(acc, reflect(k));
      return check(acc) ? k - n : -1;
    }
    propagate(k);
    int m = (l + r) >> 1;
    if (m <= st)
      return find(st, check, acc, (k << 1) | 1, m, r);
    if (st <= l && !check(f(acc, dat[k]))) {
      acc = f(acc, dat[k]);
      return -1;
    }
    int vl = find(st, check, acc, (k << 1) | 0, l, m);
    if (~vl)
      return vl;
    return find(st, check, acc, (k << 1) | 1, m, r);
  }

  template <typename C> int find(int st, C &check) {
    T acc = ti;
    return find(st, check, acc, 1, 0, n);
  }
};

struct combination {
  std::vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

ll N, K;
ll L[200010], R[200010];
mint dp[200010], S[200010];

int main() {
  std::cin >> N >> K;

  rep(i, K) std::cin >> L[i] >> R[i], ++R[i];

  auto madd = [&](mint a, mint b) { return a + b; };

  SegmentTree<mint, mint> seg(madd, madd, madd, 0, 0);

  seg.init(N + 10);
  seg.set_val(0, 1);

  rep(i, N) {
    mint x = seg.query(i, i + 1);

    rep(j, K) { seg.update(i + L[j], i + R[j], x); }
  }

  mint ans = seg.query(N - 1, N);

  std::cout << ans.x << endl;

  return 0;
}