Problem p02575 (C++) — buggy submission, verdict: Runtime Error

#pragma GCC optimize("O3")
#pragma GCC target("sse4")

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;
using namespace __gnu_pbds;
template <class T>
using Tree =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;

typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<db, db> pd;

typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<ll> vl;
typedef vector<db> vd;
typedef vector<str> vs;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<pd> vpd;

#define mp make_pair
#define f first
#define s second
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define sor(x) sort(all(x))
#define rsz resize
#define resz resize
#define ins insert
#define ft front()
#define bk back()
#define pf push_front
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound

#define f1r(i, a, b) for (int i = (a); i < (b); ++i)
#define f0r(i, a) f1r(i, 0, a)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)
#define trav(a, x) for (auto &a : x)

mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
template <class T> bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; }
template <class T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }
template <typename A, typename B>
ostream &operator<<(ostream &cout, pair<A, B> const &p) {
  return cout << "(" << p.f << ", " << p.s << ")";
}
template <typename A> ostream &operator<<(ostream &cout, vector<A> const &v) {
  cout << "[";
  for (int i = 0; i < v.size(); i++) {
    if (i)
      cout << ", ";
    cout << v[i];
  }
  return cout << "]";
}
constexpr int pct(int x) { return __builtin_popcount(x); }
constexpr int bits(int x) { return 31 - __builtin_clz(x); } // floor(log2(x))

namespace input {
template <class T> void re(complex<T> &x);
template <class T1, class T2> void re(pair<T1, T2> &p);
template <class T> void re(vector<T> &a);
template <class T, size_t SZ> void re(array<T, SZ> &a);
template <class T> void re(T &x) { cin >> x; }
void re(double &x) {
  string t;
  re(t);
  x = stod(t);
}
void re(ld &x) {
  string t;
  re(t);
  x = stold(t);
}
template <class T, class... Ts> void re(T &t, Ts &...ts) {
  re(t);
  re(ts...);
}
template <class T> void re(complex<T> &x) {
  T a, b;
  re(a, b);
  x = cd(a, b);
}
template <class T1, class T2> void re(pair<T1, T2> &p) { re(p.f, p.s); }
template <class T> void re(vector<T> &a) { F0R(i, sz(a)) re(a[i]); }
template <class T, size_t SZ> void re(array<T, SZ> &a) { F0R(i, SZ) re(a[i]); }
} // namespace input

using namespace input;

namespace output {
void pr(int x) { cout << x; }
void pr(long x) { cout << x; }
void pr(ll x) { cout << x; }
void pr(unsigned x) { cout << x; }
void pr(unsigned long x) { cout << x; }
void pr(unsigned long long x) { cout << x; }
void pr(float x) { cout << x; }
void pr(double x) { cout << x; }
void pr(ld x) { cout << x; }
void pr(char x) { cout << x; }
void pr(const char *x) { cout << x; }
void pr(const string &x) { cout << x; }
void pr(bool x) { pr(x ? "true" : "false"); }
template <class T> void pr(const complex<T> &x) { cout << x; }
template <class T1, class T2> void pr(const pair<T1, T2> &x);
template <class T> void pr(const T &x);
template <class T, class... Ts> void pr(const T &t, const Ts &...ts) {
  pr(t);
  pr(ts...);
}
template <class T1, class T2> void pr(const pair<T1, T2> &x) {
  pr("{", x.f, ", ", x.s, "}");
}
template <class T> void pr(const T &x) {
  pr("{"); // const iterator needed for vector<bool>
  bool fst = 1;
  for (const auto &a : x)
    pr(!fst ? ", " : "", a), fst = 0;
  pr("}");
}
void ps() { pr("\\n"); } // print w/ spaces
template <class T, class... Ts> void ps(const T &t, const Ts &...ts) {
  pr(t);
  if (sizeof...(ts))
    pr(" ");
  ps(ts...);
}
void pc() { pr("]\\n"); } // debug w/ commas
template <class T, class... Ts> void pc(const T &t, const Ts &...ts) {
  pr(t);
  if (sizeof...(ts))
    pr(", ");
  pc(ts...);
}
} // namespace output

using namespace output;

namespace io {
void setIn(string s) { freopen(s.c_str(), "r", stdin); }
void setOut(string s) { freopen(s.c_str(), "w", stdout); }
void setIO(string s = "") {
  cin.sync_with_stdio(0);
  cin.tie(0); // fast I/O
  // cin.exceptions(cin.failbit); // ex. throws exception when you try to read
  // letter into int
  if (sz(s)) {
    setIn(s + ".in"), setOut(s + ".out");
  } // for USACO
}
} // namespace io

using namespace io;

// DEBUG
void DBG() { cerr << "]" << endl; }
template <class H, class... T> void DBG(H h, T... t) {
  cerr << ts(h);
  if (sizeof...(t))
    cerr << ", ";
  DBG(t...);
}
#ifdef LOCAL // compile with -DLOCAL, chk -> fake assert
#define dbg(...)                                                               \\
  cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [",           \\
      DBG(__VA_ARGS__)
#define chk(...)                                                               \\
  if (!(__VA_ARGS__))                                                          \\
    cerr << "Line(" << __LINE__ << ") -> function(" << __FUNCTION__            \\
         << ") -> CHK FAILED: (" << #__VA_ARGS__ << ")"                        \\
         << "\\n",                                                              \\
        exit(0);
#else
#define dbg(...) 0
#define chk(...) 0
#endif

const int MOD = 1e9 + 7; // 998244353;
const ld PI = acos((ld)-1);

typedef decay<decltype(MOD)>::type T;
struct mi {
  T val;
  explicit operator T() const { return val; }
  mi() { val = 0; }
  mi(const ll &v) {
    val = (-MOD <= v && v <= MOD) ? v : v % MOD;
    if (val < 0)
      val += MOD;
  }
  friend ostream &operator<<(ostream &os, const mi &a) { return os << a.val; }
  friend void pr(const mi &a) { pr(a.val); }
  friend void re(mi &a) {
    ll x;
    re(x);
    a = mi(x);
  }
  friend bool operator==(const mi &a, const mi &b) { return a.val == b.val; }
  friend bool operator!=(const mi &a, const mi &b) { return !(a == b); }
  friend bool operator<(const mi &a, const mi &b) { return a.val < b.val; }
  mi operator-() const { return mi(-val); }
  mi &operator+=(const mi &m) {
    if ((val += m.val) >= MOD)
      val -= MOD;
    return *this;
  }
  mi &operator-=(const mi &m) {
    if ((val -= m.val) < 0)
      val += MOD;
    return *this;
  }
  mi &operator*=(const mi &m) {
    val = (ll)val * m.val % MOD;
    return *this;
  }
  friend mi pow(mi a, ll p) {
    mi ans = 1;
    assert(p >= 0);
    for (; p; p /= 2, a *= a)
      if (p & 1)
        ans *= a;
    return ans;
  }
  friend mi inv(const mi &a) {
    assert(a != 0);
    return pow(a, MOD - 2);
  }
  mi &operator/=(const mi &m) { return (*this) *= inv(m); }
  friend mi operator+(mi a, const mi &b) { return a += b; }
  friend mi operator-(mi a, const mi &b) { return a -= b; }
  friend mi operator*(mi a, const mi &b) { return a *= b; }
  friend mi operator/(mi a, const mi &b) { return a /= b; }
};

typedef pair<mi, mi> pmi;
typedef vector<mi> vmi;
typedef vector<pmi> vpmi;

const int INF = 1e9;
struct IntervalUnion {
  set<pi> le;
  set<pi> ri;
  multiset<ll> query;
  map<pi, int> conv;
  void add(pi x, ll y) {
    query.ins(y);
    conv[x] = y;
    le.ins(x);
    ri.ins(mp(x.s, x.f));
  }
  void rem(pi x, ll y) {
    query.erase(query.find(y));
    le.erase(x);
    ri.erase(mp(x.s, x.f));
    conv.erase(x);
  }
  ll ask() { return *query.begin(); }
  vpi intersect(pi x) {
    pi use1 = mp(x.f, -INF);
    pi use2 = mp(x.s, INF);
    auto it1 = le.lb(use1);
    auto it2 = ri.lb(use2);
    set<pi> bad;
    vpi ret;
    if (it2 != ri.end()) {
      int lo = (*it2).s;
      int hi = (*it2).f;
      if (lo <= x.f && x.s <= hi) {
        ret.eb(mp(lo, hi));
        return ret;
      }
    }
    if (it1 != le.end()) {
      while (it1 != le.end()) {
        auto val = (*it1);
        if (val.f <= x.s) {
          bad.insert(val);
        } else {
          break;
        }
        it1 = next(it1);
      }
    }
    if (it2 != ri.begin()) {
      it2 = prev(it2);
      while (true) {
        auto val = (*it2);
        if (val.f >= x.f) {
          bad.insert(mp(val.s, val.f));
        } else
          break;
        if (it2 == ri.begin())
          break;
        it2 = prev(it2);
      }
    }
    for (auto b : bad)
      ret.eb(b);
    return ret;
  }
};
const int MAX = 2e5 + 5;
int l[MAX], r[MAX];
IntervalUnion I;
int main() {
  setIO("");
  int h, w;
  re(h, w);
  f0r(i, h) re(l[i], r[i]);
  f0r(i, h) l[i]--, r[i]--;
  f0r(i, w) I.add(mp(i, i), 0);
  f1r(i, 1, h + 1) {
    int L = l[i - 1];
    int R = r[i - 1];

    vpi use = I.intersect(mp(L, R));
    ll st = INF;
    pi beg = mp(INF, INF);
    ll begval = -1;
    if (use[0].f < L) {
      st = I.conv[use[0]] + L - use[0].f;
      beg = mp(use[0].f, L - 1);
      begval = I.conv[use[0]];
    } else {
      if (L != 0) {
        auto bef = *(I.ri).lb(mp(L - 1, -INF));
        st = I.conv[mp(bef.s, bef.f)] + L - bef.s;
      }
    }
    pi last = mp(INF, INF);
    ll val = -1;
    if (use.back().s != R) {
      last = mp(R + 1, use.back().s);
      val = I.conv[use.back()] + R + 1 - use.back().f;
    }
    for (auto x : use)
      I.rem(x, I.conv[x]);
    I.add(mp(L, R), st);
    if (val != -1) {
      I.add(last, val);
    }
    if (begval != -1) {
      I.add(beg, begval);
    }
    ll res = I.ask() + i;
    if (res >= INF)
      ps(-1);
    else
      ps(res);
  }
  return 0;
}


Error: 0

Fixed submission:

#pragma GCC optimize("O3")
#pragma GCC target("sse4")

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;
using namespace __gnu_pbds;
template <class T>
using Tree =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;

typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<db, db> pd;

typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<ll> vl;
typedef vector<db> vd;
typedef vector<str> vs;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<pd> vpd;

#define mp make_pair
#define f first
#define s second
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define sor(x) sort(all(x))
#define rsz resize
#define resz resize
#define ins insert
#define ft front()
#define bk back()
#define pf push_front
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound

#define f1r(i, a, b) for (int i = (a); i < (b); ++i)
#define f0r(i, a) f1r(i, 0, a)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)
#define trav(a, x) for (auto &a : x)

mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
template <class T> bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; }
template <class T> bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }
template <typename A, typename B>
ostream &operator<<(ostream &cout, pair<A, B> const &p) {
  return cout << "(" << p.f << ", " << p.s << ")";
}
template <typename A> ostream &operator<<(ostream &cout, vector<A> const &v) {
  cout << "[";
  for (int i = 0; i < v.size(); i++) {
    if (i)
      cout << ", ";
    cout << v[i];
  }
  return cout << "]";
}
constexpr int pct(int x) { return __builtin_popcount(x); }
constexpr int bits(int x) { return 31 - __builtin_clz(x); } // floor(log2(x))

namespace input {
template <class T> void re(complex<T> &x);
template <class T1, class T2> void re(pair<T1, T2> &p);
template <class T> void re(vector<T> &a);
template <class T, size_t SZ> void re(array<T, SZ> &a);
template <class T> void re(T &x) { cin >> x; }
void re(double &x) {
  string t;
  re(t);
  x = stod(t);
}
void re(ld &x) {
  string t;
  re(t);
  x = stold(t);
}
template <class T, class... Ts> void re(T &t, Ts &...ts) {
  re(t);
  re(ts...);
}
template <class T> void re(complex<T> &x) {
  T a, b;
  re(a, b);
  x = cd(a, b);
}
template <class T1, class T2> void re(pair<T1, T2> &p) { re(p.f, p.s); }
template <class T> void re(vector<T> &a) { F0R(i, sz(a)) re(a[i]); }
template <class T, size_t SZ> void re(array<T, SZ> &a) { F0R(i, SZ) re(a[i]); }
} // namespace input

using namespace input;

namespace output {
void pr(int x) { cout << x; }
void pr(long x) { cout << x; }
void pr(ll x) { cout << x; }
void pr(unsigned x) { cout << x; }
void pr(unsigned long x) { cout << x; }
void pr(unsigned long long x) { cout << x; }
void pr(float x) { cout << x; }
void pr(double x) { cout << x; }
void pr(ld x) { cout << x; }
void pr(char x) { cout << x; }
void pr(const char *x) { cout << x; }
void pr(const string &x) { cout << x; }
void pr(bool x) { pr(x ? "true" : "false"); }
template <class T> void pr(const complex<T> &x) { cout << x; }
template <class T1, class T2> void pr(const pair<T1, T2> &x);
template <class T> void pr(const T &x);
template <class T, class... Ts> void pr(const T &t, const Ts &...ts) {
  pr(t);
  pr(ts...);
}
template <class T1, class T2> void pr(const pair<T1, T2> &x) {
  pr("{", x.f, ", ", x.s, "}");
}
template <class T> void pr(const T &x) {
  pr("{"); // const iterator needed for vector<bool>
  bool fst = 1;
  for (const auto &a : x)
    pr(!fst ? ", " : "", a), fst = 0;
  pr("}");
}
void ps() { pr("\\n"); } // print w/ spaces
template <class T, class... Ts> void ps(const T &t, const Ts &...ts) {
  pr(t);
  if (sizeof...(ts))
    pr(" ");
  ps(ts...);
}
void pc() { pr("]\\n"); } // debug w/ commas
template <class T, class... Ts> void pc(const T &t, const Ts &...ts) {
  pr(t);
  if (sizeof...(ts))
    pr(", ");
  pc(ts...);
}
} // namespace output

using namespace output;

namespace io {
void setIn(string s) { freopen(s.c_str(), "r", stdin); }
void setOut(string s) { freopen(s.c_str(), "w", stdout); }
void setIO(string s = "") {
  cin.sync_with_stdio(0);
  cin.tie(0); // fast I/O
  // cin.exceptions(cin.failbit); // ex. throws exception when you try to read
  // letter into int
  if (sz(s)) {
    setIn(s + ".in"), setOut(s + ".out");
  } // for USACO
}
} // namespace io

using namespace io;

// DEBUG
void DBG() { cerr << "]" << endl; }
template <class H, class... T> void DBG(H h, T... t) {
  cerr << ts(h);
  if (sizeof...(t))
    cerr << ", ";
  DBG(t...);
}
#ifdef LOCAL // compile with -DLOCAL, chk -> fake assert
#define dbg(...)                                                               \\
  cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [",           \\
      DBG(__VA_ARGS__)
#define chk(...)                                                               \\
  if (!(__VA_ARGS__))                                                          \\
    cerr << "Line(" << __LINE__ << ") -> function(" << __FUNCTION__            \\
         << ") -> CHK FAILED: (" << #__VA_ARGS__ << ")"                        \\
         << "\\n",                                                              \\
        exit(0);
#else
#define dbg(...) 0
#define chk(...) 0
#endif

const int MOD = 1e9 + 7; // 998244353;
const ld PI = acos((ld)-1);

typedef decay<decltype(MOD)>::type T;
struct mi {
  T val;
  explicit operator T() const { return val; }
  mi() { val = 0; }
  mi(const ll &v) {
    val = (-MOD <= v && v <= MOD) ? v : v % MOD;
    if (val < 0)
      val += MOD;
  }
  friend ostream &operator<<(ostream &os, const mi &a) { return os << a.val; }
  friend void pr(const mi &a) { pr(a.val); }
  friend void re(mi &a) {
    ll x;
    re(x);
    a = mi(x);
  }
  friend bool operator==(const mi &a, const mi &b) { return a.val == b.val; }
  friend bool operator!=(const mi &a, const mi &b) { return !(a == b); }
  friend bool operator<(const mi &a, const mi &b) { return a.val < b.val; }
  mi operator-() const { return mi(-val); }
  mi &operator+=(const mi &m) {
    if ((val += m.val) >= MOD)
      val -= MOD;
    return *this;
  }
  mi &operator-=(const mi &m) {
    if ((val -= m.val) < 0)
      val += MOD;
    return *this;
  }
  mi &operator*=(const mi &m) {
    val = (ll)val * m.val % MOD;
    return *this;
  }
  friend mi pow(mi a, ll p) {
    mi ans = 1;
    assert(p >= 0);
    for (; p; p /= 2, a *= a)
      if (p & 1)
        ans *= a;
    return ans;
  }
  friend mi inv(const mi &a) {
    assert(a != 0);
    return pow(a, MOD - 2);
  }
  mi &operator/=(const mi &m) { return (*this) *= inv(m); }
  friend mi operator+(mi a, const mi &b) { return a += b; }
  friend mi operator-(mi a, const mi &b) { return a -= b; }
  friend mi operator*(mi a, const mi &b) { return a *= b; }
  friend mi operator/(mi a, const mi &b) { return a /= b; }
};

typedef pair<mi, mi> pmi;
typedef vector<mi> vmi;
typedef vector<pmi> vpmi;

const int INF = 1e9;
struct IntervalUnion {
  set<pi> le;
  set<pi> ri;
  multiset<ll> query;
  map<pi, int> conv;
  void add(pi x, ll y) {
    query.ins(y);
    conv[x] = y;
    le.ins(x);
    ri.ins(mp(x.s, x.f));
  }
  void rem(pi x, ll y) {
    query.erase(query.find(y));
    le.erase(x);
    ri.erase(mp(x.s, x.f));
    conv.erase(x);
  }
  ll ask() { return *query.begin(); }
  vpi intersect(pi x) {
    pi use1 = mp(x.f, -INF);
    pi use2 = mp(x.s, INF);
    auto it1 = le.lb(use1);
    auto it2 = ri.lb(use2);
    set<pi> bad;
    vpi ret;
    if (it2 != ri.end()) {
      int lo = (*it2).s;
      int hi = (*it2).f;
      if (lo <= x.f && x.s <= hi) {
        ret.eb(mp(lo, hi));
        return ret;
      }
    }
    if (it1 != le.end()) {
      while (it1 != le.end()) {
        auto val = (*it1);
        if (val.f <= x.s) {
          bad.insert(val);
        } else {
          break;
        }
        it1 = next(it1);
      }
    }
    if (it2 != ri.begin()) {
      it2 = prev(it2);
      while (true) {
        auto val = (*it2);
        if (val.f >= x.f) {
          bad.insert(mp(val.s, val.f));
        } else
          break;
        if (it2 == ri.begin())
          break;
        it2 = prev(it2);
      }
    }
    for (auto b : bad)
      ret.eb(b);
    return ret;
  }
};
const int MAX = 2e5 + 5;
int l[MAX], r[MAX];
int ans[MAX];
IntervalUnion I;
int main() {
  setIO("");
  int h, w;
  re(h, w);
  f0r(i, h) re(l[i], r[i]);
  f0r(i, h) l[i]--, r[i]--;
  f0r(i, w) I.add(mp(i, i), 0);
  f1r(i, 1, h + 1) {
    int L = l[i - 1];
    int R = r[i - 1];

    vpi use = I.intersect(mp(L, R));
    ll st = INF;
    if (use[0].f < L) {
      st = I.conv[use[0]] + L - use[0].f;
    } else {
      if (L != 0) {
        auto bef = *(I.ri).lb(mp(L - 1, -INF));
        st = I.conv[mp(bef.s, bef.f)] + L - bef.f;
      }
    }
    pi last = mp(INF, INF);
    ll val = -1;
    if (use.back().s != R) {
      last = mp(R + 1, use.back().s);
      val = I.conv[use.back()] + use.back().s - use.back().f;
    }
    for (auto x : use)
      I.rem(x, I.conv[x]);
    I.add(mp(L, R), st);
    if (val != -1) {
      I.add(last, val);
    }
    //        ps(I.le, I.conv);
    ll res = I.ask() + i;
    if (res >= INF)
      ps(-1);
    else
      ps(res);
  }
  return 0;
}