Problem p02575 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>

namespace atcoder {

namespace internal {

// @param n `0 <= n`
// @return minimum non-negative `x` s.t. `n <= 2**x`
int ceil_pow2(int n) {
  int x = 0;
  while ((1U << x) < (unsigned int)(n))
    x++;
  return x;
}

// @param n `1 <= n`
// @return minimum non-negative `x` s.t. `(n & (1 << x)) != 0`
int bsf(unsigned int n) {
#ifdef _MSC_VER
  unsigned long index;
  _BitScanForward(&index, n);
  return index;
#else
  return __builtin_ctz(n);
#endif
}

} // namespace internal

} // namespace atcoder

namespace atcoder {

template <class S, S (*op)(S, S), S (*e)(), class F, S (*mapping)(F, S),
          F (*composition)(F, F), F (*id)()>
struct lazy_segtree {
public:
  lazy_segtree() : lazy_segtree(0) {}
  lazy_segtree(int n) : lazy_segtree(std::vector<S>(n, e())) {}
  lazy_segtree(const std::vector<S> &v) : _n(int(v.size())) {
    log = internal::ceil_pow2(_n);
    size = 1 << log;
    d = std::vector<S>(2 * size, e());
    lz = std::vector<F>(size, id());
    for (int i = 0; i < _n; i++)
      d[size + i] = v[i];
    for (int i = size - 1; i >= 1; i--) {
      update(i);
    }
  }

  void set(int p, S x) {
    assert(0 <= p && p < _n);
    p += size;
    for (int i = log; i >= 1; i--)
      push(p >> i);
    d[p] = x;
    for (int i = 1; i <= log; i++)
      update(p >> i);
  }

  S get(int p) {
    assert(0 <= p && p < _n);
    p += size;
    for (int i = log; i >= 1; i--)
      push(p >> i);
    return d[p];
  }

  S prod(int l, int r) {
    assert(0 <= l && l <= r && r <= _n);
    if (l == r)
      return e();

    l += size;
    r += size;

    for (int i = log; i >= 1; i--) {
      if (((l >> i) << i) != l)
        push(l >> i);
      if (((r >> i) << i) != r)
        push(r >> i);
    }

    S sml = e(), smr = e();
    while (l < r) {
      if (l & 1)
        sml = op(sml, d[l++]);
      if (r & 1)
        smr = op(d[--r], smr);
      l >>= 1;
      r >>= 1;
    }

    return op(sml, smr);
  }

  S all_prod() { return d[1]; }

  void apply(int p, F f) {
    assert(0 <= p && p < _n);
    p += size;
    for (int i = log; i >= 1; i--)
      push(p >> i);
    d[p] = mapping(f, d[p]);
    for (int i = 1; i <= log; i++)
      update(p >> i);
  }
  void apply(int l, int r, F f) {
    assert(0 <= l && l <= r && r <= _n);
    if (l == r)
      return;

    l += size;
    r += size;

    for (int i = log; i >= 1; i--) {
      if (((l >> i) << i) != l)
        push(l >> i);
      if (((r >> i) << i) != r)
        push((r - 1) >> i);
    }

    {
      int l2 = l, r2 = r;
      while (l < r) {
        if (l & 1)
          all_apply(l++, f);
        if (r & 1)
          all_apply(--r, f);
        l >>= 1;
        r >>= 1;
      }
      l = l2;
      r = r2;
    }

    for (int i = 1; i <= log; i++) {
      if (((l >> i) << i) != l)
        update(l >> i);
      if (((r >> i) << i) != r)
        update((r - 1) >> i);
    }
  }

  template <bool (*g)(S)> int max_right(int l) {
    return max_right(l, [](S x) { return g(x); });
  }
  template <class G> int max_right(int l, G g) {
    assert(0 <= l && l <= _n);
    assert(g(e()));
    if (l == _n)
      return _n;
    l += size;
    for (int i = log; i >= 1; i--)
      push(l >> i);
    S sm = e();
    do {
      while (l % 2 == 0)
        l >>= 1;
      if (!g(op(sm, d[l]))) {
        while (l < size) {
          push(l);
          l = (2 * l);
          if (g(op(sm, d[l]))) {
            sm = op(sm, d[l]);
            l++;
          }
        }
        return l - size;
      }
      sm = op(sm, d[l]);
      l++;
    } while ((l & -l) != l);
    return _n;
  }

  template <bool (*g)(S)> int min_left(int r) {
    return min_left(r, [](S x) { return g(x); });
  }
  template <class G> int min_left(int r, G g) {
    assert(0 <= r && r <= _n);
    assert(g(e()));
    if (r == 0)
      return 0;
    r += size;
    for (int i = log; i >= 1; i--)
      push((r - 1) >> i);
    S sm = e();
    do {
      r--;
      while (r > 1 && (r % 2))
        r >>= 1;
      if (!g(op(d[r], sm))) {
        while (r < size) {
          push(r);
          r = (2 * r + 1);
          if (g(op(d[r], sm))) {
            sm = op(d[r], sm);
            r--;
          }
        }
        return r + 1 - size;
      }
      sm = op(d[r], sm);
    } while ((r & -r) != r);
    return 0;
  }

private:
  int _n, size, log;
  std::vector<S> d;
  std::vector<F> lz;

  void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
  void all_apply(int k, F f) {
    d[k] = mapping(f, d[k]);
    if (k < size)
      lz[k] = composition(f, lz[k]);
  }
  void push(int k) {
    all_apply(2 * k, lz[k]);
    all_apply(2 * k + 1, lz[k]);
    lz[k] = id();
  }
};

} // namespace atcoder

using namespace std;

using ll = long long int;

inline void fast_io() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
};
template <typename T> inline vector<T> fetch_vec(int sz) {
  vector<T> ret(sz);
  for (auto &elem : ret)
    cin >> elem;
  return ret;
}

int H, W;
vector<int> A, B;
void input() {
  fast_io();
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    int a, b;
    cin >> a >> b;
    a--, b--;
    A.push_back(a);
    B.push_back(b);
  }
}

ll INF = (ll)1e9;
struct S {
  ll x, i;
};
S op(S x, S y) { return S{min(x.x, y.x), min(x.i, y.i)}; }
S e() { return S{INF, INF}; }
struct F {
  ll a, b, c;
};
S mapping(F f, S x) { return S{f.a * x.x + f.b * x.i + f.c, x.i}; }
F composition(F f, F g) {
  return F{f.a * g.a, f.b + f.a * g.b, f.c + f.a * g.c};
}
F id() { return F{1, 0, 0}; }

int solve() {
  vector<S> Init(W);
  for (int j = 0; j < W; j++) {
    Init[j] = S{0, j};
  }

  atcoder::lazy_segtree<S, op, e, F, mapping, composition, id> seg(Init);
  vector<ll> Ans;
  for (int h = 0; h < H; h++) {
    ll a;
    if (A[h] > 0)
      a = seg.prod(A[h] - 1, A[h]).x;

    if (A[h] == 0 || a >= INF) {
      F f{0, 0, INF};
      seg.apply(A[h], B[h] + 1, f);
      Ans.push_back(h + 1 + seg.all_prod().x);
    } else {
      F f{0, 1, a - (A[h] - 1)};
      seg.apply(A[h], B[h] + 1, f);
      Ans.push_back(h + 1 + seg.all_prod().x);
    }
  }
  for (auto x : Ans) {
    if (x >= INF)
      cout << -1 << endl;
    else
      cout << x << endl;
  }
  return 0;
}

int TLEsolve() {
  vector<ll> cost(W, 0);
  vector<ll> Ans;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (A[i] <= j && j <= B[i]) {
        cost[j] = 1e6;
      } else {
        cost[j]++;
      }
      if (j)
        cost[j] = min(cost[j], cost[j - 1] + 1);
    }
    int ans = *min_element(cost.begin(), cost.end());
    if (ans >= 1e6)
      ans = -1;
    // cout << ans << endl;
    Ans.push_back(ans);
  }
  for (auto x : Ans)
    cout << x << "\\n";
  return 0;
}

int main() {
  input();
  solve();
  return 0;
}

Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#ifdef __DEBUG__
#define DBG(X) cout << #X << " = " << (X) << endl;
#define SAY(X) cout << (X) << endl;
#else
#define DBG(X)
#define SAY(X)
#endif

using namespace std;

using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, 1, -1, -1};
const int INT_INF = (int)(2e9);
const ll LL_INF = (ll)(2e18);

inline void fast_io() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
};
template <typename T, typename S>
inline ostream &operator<<(ostream &os, const pair<T, S> p) {
  cout << "[" << p.first << ";" << p.second << "]";
  return os;
}
template <typename T, typename S>
inline ostream &operator<<(ostream &os, const map<T, S> p) {
  for (auto el : p)
    cout << "[" << el.first << ";" << el.second << "]";
  return os;
}
template <typename T>
inline ostream &operator<<(ostream &os, const vector<T> &v) {
  for (auto el : v)
    cout << el << " ";
  return os;
}
template <typename T>
inline ostream &operator<<(ostream &os, const deque<T> &v) {
  for (auto el : v)
    cout << el << " ";
  return os;
}
template <typename T> inline ostream &operator<<(ostream &os, const set<T> &v) {
  for (auto el : v)
    cout << el << " ";
  return os;
}
template <typename T> inline vector<T> fetch_vec(int sz) {
  vector<T> ret(sz);
  for (auto &elem : ret)
    cin >> elem;
  return ret;
}

int H, W;
vector<int> A, B;
void input() {
  fast_io();
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    int a, b;
    cin >> a >> b;
    a--, b--;
    A.push_back(a);
    B.push_back(b);
  }
}

int solve() {
  vector<ll> most_left(H + 1, -1LL);
  vector<ll> most_right(H + 1, -1LL);
  int col = 0;
  for (int i = 0; i < H; i++) {
    if ((A[i] <= col) && (col <= B[i])) {
      col = B[i] + 1;
    }
    if (col < W) {
      most_left[i + 1] = col;
    } else {
      break;
    }
  }
  col = W - 1;
  for (int i = H - 1; i >= 0; i--) {
    if (most_left[i + 1] == -1LL)
      continue;
    else if ((A[i] <= col) && (col <= B[i])) {
      col = A[i] - 1;
      most_right[i + 1] = col;
    }
  }

  return 0;
}

int TLEsolve() {
  vector<ll> cost(W, 0);
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (A[i] <= j && j <= B[i]) {
        cost[j] = 1e6;
      } else {
        cost[j]++;
      }
      if (j)
        cost[j] = min(cost[j], cost[j - 1] + 1);
    }
    int ans = *min_element(cost.begin(), cost.end());
    if (ans >= 1e6)
      ans = -1;
    cout << ans << endl;
  }
  return 0;
}

int main() {
  input();
  TLEsolve();
  return 0;
}