Problem p02647 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <complex>
#include <cstdint>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <math.h>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <stdio.h>
#include <string>
#include <time.h>
#include <utility>
#include <vector>
using namespace std;
using pii = pair<int, int>;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define sc second
#define fr first
#define stpr setprecision
#define cYES cout << "YES" << endl
#define cNO cout << "NO" << endl
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define Rep(i, a, b) for (ll i = (a); i < (b); ++i)
#define rrep(i, n) for (ll i = n - 1; i >= 0; i--)
#define rRep(i, a, b) for (ll i = a; i >= b; i--)
#define crep(i) for (char i = 'a'; i <= 'z'; ++i)
#define psortsecond(A, N)                                                      \\
  sort(A, A + N,                                                               \\
       [](const pii &a, const pii &b) { return a.second < b.second; });
#define ALL(x) (x).begin(), (x).end()
#define debug(v)                                                               \\
  cout << #v << ":";                                                           \\
  for (auto x : v) {                                                           \\
    cout << x << ' ';                                                          \\
  }                                                                            \\
  cout << endl;
#define endl '\\n'
int ctoi(const char c) {
  if ('0' <= c && c <= '9')
    return (c - '0');
  return -1;
}
ll gcd(ll a, ll b) { return (b == 0 ? a : gcd(b, a % b)); }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
constexpr ll MOD = 1000000007;
constexpr ll INF = 1000000011;
constexpr ll MOD2 = 998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS = 10e-8;
template <class T, class U> inline bool chmax(T &lhs, const U &rhs) {
  if (lhs < rhs) {
    lhs = rhs;
    return 1;
  }
  return 0;
}
template <class T, class U> inline bool chmin(T &lhs, const U &rhs) {
  if (lhs > rhs) {
    lhs = rhs;
    return 1;
  }
  return 0;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &&x : v)
    is >> x;
  return is;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first;
  is >> p.second;
  return is;
}
template <typename T, typename U>
ostream &operator>>(ostream &os, const pair<T, U> &p) {
  os << p.first << ' ' << p.second;
  return os;
}
template <class T> ostream &operator<<(ostream &os, vector<T> &v) {
  for (auto i = begin(v); i != end(v); ++i) {
    if (i != begin(v))
      os << ' ';
    os << *i;
  }
  return os;
}

ll A[200007], B[200007];

signed main() {
  ll N, Q, K;
  cin >> N >> K;
  vector<ll> V;
  ll Z = 0;
  V = vector<ll>(N + 1, 0);
  rep(i, N) {
    cin >> V[i];
    if (V[i] == N) {
      Z++;
    }
  }
  rep(i, K) {
    if (Z == N) {
      rep(i, N) {
        cout << N;
        if (i == N - 1) {
          cout << endl;
        } else {
          cout << " ";
        }
      }
      return 0;
    }
    Z = 0;
    rep(j, N) { B[j] = 0; }
    rep(j, N) {
      B[max(0ll, j - V[j])]++;
      B[min((ll)N, j + V[j]) + 1]--;
    }
    rep(j, N) {
      if (j == 0) {
        V[j] = B[j];
      } else {
        V[j] = V[j - 1] + B[j];
      }
      if (V[j] == N) {
        Z++;
      }
    }
  }
  rep(i, N) {
    cout << V[i];
    if (i != N - 1) {
      cout << " ";
    }
  }
  cout << endl;
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <complex>
#include <cstdint>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <math.h>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <stdio.h>
#include <string>
#include <time.h>
#include <utility>
#include <vector>
using namespace std;
using pii = pair<int, int>;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define sc second
#define fr first
#define stpr setprecision
#define cYES cout << "YES" << endl
#define cNO cout << "NO" << endl
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define Rep(i, a, b) for (ll i = (a); i < (b); ++i)
#define rrep(i, n) for (ll i = n - 1; i >= 0; i--)
#define rRep(i, a, b) for (ll i = a; i >= b; i--)
#define crep(i) for (char i = 'a'; i <= 'z'; ++i)
#define psortsecond(A, N)                                                      \\
  sort(A, A + N,                                                               \\
       [](const pii &a, const pii &b) { return a.second < b.second; });
#define ALL(x) (x).begin(), (x).end()
#define debug(v)                                                               \\
  cout << #v << ":";                                                           \\
  for (auto x : v) {                                                           \\
    cout << x << ' ';                                                          \\
  }                                                                            \\
  cout << endl;
#define endl '\\n'
int ctoi(const char c) {
  if ('0' <= c && c <= '9')
    return (c - '0');
  return -1;
}
ll gcd(ll a, ll b) { return (b == 0 ? a : gcd(b, a % b)); }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
constexpr ll MOD = 1000000007;
constexpr ll INF = 1000000011;
constexpr ll MOD2 = 998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS = 10e-8;
template <class T, class U> inline bool chmax(T &lhs, const U &rhs) {
  if (lhs < rhs) {
    lhs = rhs;
    return 1;
  }
  return 0;
}
template <class T, class U> inline bool chmin(T &lhs, const U &rhs) {
  if (lhs > rhs) {
    lhs = rhs;
    return 1;
  }
  return 0;
}
template <typename T> istream &operator>>(istream &is, vector<T> &v) {
  for (auto &&x : v)
    is >> x;
  return is;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first;
  is >> p.second;
  return is;
}
template <typename T, typename U>
ostream &operator>>(ostream &os, const pair<T, U> &p) {
  os << p.first << ' ' << p.second;
  return os;
}
template <class T> ostream &operator<<(ostream &os, vector<T> &v) {
  for (auto i = begin(v); i != end(v); ++i) {
    if (i != begin(v))
      os << ' ';
    os << *i;
  }
  return os;
}

ll plu(ll a, ll b) { return a + b; }

template <typename T, typename E> struct SegmentTree {
  using F = function<T(T, T)>; // dat計算時に　dat[k] = f(子１、子２) となる
  using G = function<T(T, E)>; // 更新時に  dat[k] = g(dat[k],laz[k])となる
  using H = function<E(E, E)>; // updateで　laz[k] = h(laz[k],x) となる
  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 eval(int k) {
    if (laz[k] == ei)
      return;
    laz[(k << 1) | 0] =
        h(laz[(k << 1) | 0], laz[k] / 2); // RAQではここで右変数を割る２
    laz[(k << 1) | 1] =
        h(laz[(k << 1) | 1], laz[k] / 2); // RAQではここで右変数を割る２
    dat[k] = reflect(k);
    laz[k] = ei;
  }
  inline void thrust(int k) {
    for (int i = height; i; i--)
      eval(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) {
    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);
      // RAQ↓が必要
      x <<= 1;
    }
    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) {
    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);
  }
};

ll A[200007];

signed main() {
  int N, Q, K;
  cin >> N >> K;
  SegmentTree<ll, ll> rsq(plu, plu, plu, 0LL, 0LL);
  vector<ll> V;
  V = vector<ll>(N + 1, 0);
  rep(i, N) { cin >> V[i]; }
  rsq.build(V);
  rep(i, K) {
    if (i != 0 && rsq.query(0, N) == N * N) {
      rep(i, N) {
        cout << N;
        if (i == N - 1) {
          cout << endl;
        } else {
          cout << " ";
        }
      }
      return 0;
    }
    rep(j, N) {
      A[j] = rsq.query(j, j + 1);
      rsq.update(j, j + 1, -A[j]);
    }
    rep(j, N) {
      ll T = A[j];
      rsq.update(max(0ll, j - T), min((ll)N, j + T + 1), 1);
    }
  }
  rep(i, N) {
    cout << rsq.query(i, i + 1);
    if (i != N - 1) {
      cout << " ";
    }
  }
  cout << endl;
}