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

#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
#define REP(i, k, n) for (long long i = k; i < (long long)(n); i++)
#define all(a) a.begin(), a.end()
#define pb emplace_back
#define eb emplace_back
#define lb(v, k) (lower_bound(all(v), k) - v.begin())
#define ub(v, k) (upper_bound(all(v), k) - v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T, vector<T>, greater<T>>
#define dame(a)                                                                \\
  {                                                                            \\
    out(a);                                                                    \\
    return 0;                                                                  \\
  }
#define decimal cout << fixed << setprecision(15);
#define dupli(a) a.erase(unique(all(a)), a.end())
typedef long long ll;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> PP;
typedef tuple<ll, ll, ll, ll> PPP;
typedef multiset<ll> S;
using vi = vector<ll>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;
using vp = vector<P>;
using vvp = vector<vp>;
using vb = vector<bool>;
using vvb = vector<vb>;
const ll inf = 1001001001001001001;
const ll INF = 1001001001;
const ll mod = 1000000007;
const double eps = 1e-10;
template <class T> bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> void out(T a) { cout << a << '\\n'; }
template <class T> void outp(T a) {
  cout << '(' << a.fi << ',' << a.se << ')' << '\\n';
}
template <class T> void outvp(T v) {
  rep(i, v.size()) cout << '(' << v[i].fi << ',' << v[i].se << ')';
  cout << '\\n';
}
template <class T> void outvvp(T v) { rep(i, v.size()) outvp(v[i]); }
template <class T> void outv(T v) {
  rep(i, v.size()) {
    if (i)
      cout << ' ';
    cout << v[i];
  }
  cout << '\\n';
}
template <class T> void outvv(T v) { rep(i, v.size()) outv(v[i]); }
template <class T> bool isin(T x, T l, T r) { return (l) <= (x) && (x) <= (r); }
template <class T> void yesno(T b) {
  if (b)
    out("yes");
  else
    out("no");
}
template <class T> void YesNo(T b) {
  if (b)
    out("Yes");
  else
    out("No");
}
template <class T> void YESNO(T b) {
  if (b)
    out("YES");
  else
    out("NO");
}
template <class T> void noyes(T b) {
  if (b)
    out("no");
  else
    out("yes");
}
template <class T> void NoYes(T b) {
  if (b)
    out("No");
  else
    out("Yes");
}
template <class T> void NOYES(T b) {
  if (b)
    out("NO");
  else
    out("YES");
}
void outs(ll a, ll b) {
  if (a >= inf - 100)
    out(b);
  else
    out(a);
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll modpow(ll a, ll b) {
  ll res = 1;
  a %= mod;
  while (b) {
    if (b & 1)
      res = res * a % mod;
    a = a * a % mod;
    b >>= 1;
  }
  return res;
}

void solve() {
  ll n, k;
  cin >> n >> k;
  vi v(n);
  rep(i, n) cin >> v[i];
  rep(i, k) {
    vi nv(n);
    rep(j, n) {
      nv[max(j - v[j], 0ll)]++;
      if (j + v[j] + 1 < n)
        nv[j + v[j] + 1]--;
      // REP(t,max(j-v[j],0ll),min(j+v[j]+1,n))nv[t]++;
    }
    // outv(nv);
    REP(j, 1, n) nv[j] += nv[j - 1];
    bool ok = true;
    rep(j, n) if (nv[j] != n) ok = false;
    v = nv;
    if (ok)
      break;
  }
  outv(v);
}
signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  solve();
}

Error: TLE

Fixed submission:

#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
#define REP(i, k, n) for (long long i = k; i < (long long)(n); i++)
#define all(a) a.begin(), a.end()
#define pb emplace_back
#define eb emplace_back
#define lb(v, k) (lower_bound(all(v), k) - v.begin())
#define ub(v, k) (upper_bound(all(v), k) - v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T, vector<T>, greater<T>>
#define dame(a)                                                                \\
  {                                                                            \\
    out(a);                                                                    \\
    return 0;                                                                  \\
  }
#define decimal cout << fixed << setprecision(15);
#define dupli(a) a.erase(unique(all(a)), a.end())
typedef long long ll;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> PP;
typedef tuple<ll, ll, ll, ll> PPP;
typedef multiset<ll> S;
using vi = vector<ll>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;
using vp = vector<P>;
using vvp = vector<vp>;
using vb = vector<bool>;
using vvb = vector<vb>;
const ll inf = 1001001001001001001;
const ll INF = 1001001001;
const ll mod = 1000000007;
const double eps = 1e-10;
template <class T> bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> void out(T a) { cout << a << '\\n'; }
template <class T> void outp(T a) {
  cout << '(' << a.fi << ',' << a.se << ')' << '\\n';
}
template <class T> void outvp(T v) {
  rep(i, v.size()) cout << '(' << v[i].fi << ',' << v[i].se << ')';
  cout << '\\n';
}
template <class T> void outvvp(T v) { rep(i, v.size()) outvp(v[i]); }
template <class T> void outv(T v) {
  rep(i, v.size()) {
    if (i)
      cout << ' ';
    cout << v[i];
  }
  cout << '\\n';
}
template <class T> void outvv(T v) { rep(i, v.size()) outv(v[i]); }
template <class T> bool isin(T x, T l, T r) { return (l) <= (x) && (x) <= (r); }
template <class T> void yesno(T b) {
  if (b)
    out("yes");
  else
    out("no");
}
template <class T> void YesNo(T b) {
  if (b)
    out("Yes");
  else
    out("No");
}
template <class T> void YESNO(T b) {
  if (b)
    out("YES");
  else
    out("NO");
}
template <class T> void noyes(T b) {
  if (b)
    out("no");
  else
    out("yes");
}
template <class T> void NoYes(T b) {
  if (b)
    out("No");
  else
    out("Yes");
}
template <class T> void NOYES(T b) {
  if (b)
    out("NO");
  else
    out("YES");
}
void outs(ll a, ll b) {
  if (a >= inf - 100)
    out(b);
  else
    out(a);
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll modpow(ll a, ll b) {
  ll res = 1;
  a %= mod;
  while (b) {
    if (b & 1)
      res = res * a % mod;
    a = a * a % mod;
    b >>= 1;
  }
  return res;
}

void solve() {
  ll n, k;
  cin >> n >> k;
  vi v(n);
  rep(i, n) cin >> v[i];
  rep(i, k) {
    vi nv(n);
    rep(j, n) {
      nv[max(j - v[j], 0ll)]++;
      if (j + v[j] + 1 < n)
        nv[j + v[j] + 1]--;
      // REP(t,max(j-v[j],0ll),min(j+v[j]+1,n))nv[t]++;
    }
    // outv(nv);
    REP(j, 1, n) nv[j] += nv[j - 1];
    v = nv;
  }
  outv(v);
}
signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  solve();
}