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

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;

#define all(v) v.begin(), v.end()

const ll mod = 1000000007;

ll countBits(ll in) {
  int res = 0;
  for (; in > 0; in >>= 1) {
    if ((in & 0x01) != 0) {
      res++;
    }
  }
  return res;
}

template <typename T> void show2dVector(vector<vector<T>> &v) {
  for (int i = 0; i < v.size(); i++) {
    int m = v[i].size();
    cout << i << " : ";
    for (int j = 0; i < m; i++) {
      cout << v[i][j] << " ";
    }
    cout << endl;
  }
}

void bfs(const vector<vector<int>> &g, int v, vector<bool> &seen) {
  seen[v] = true;
  cout << v << " ";
  for (auto next : g[v]) {
    if (seen[next]) {
      continue;
    }
    bfs(g, next, seen);
  }
}

bool dfs(vector<vector<int>> &g, int start, int goal, vector<bool> &seen) {
  bool res = false;
  seen[start] = true;
  if (start == goal) {
    return true;
  }
  for (auto next : g[start]) {
    if (seen[next]) {
      continue;
    }
    res = dfs(g, next, goal, seen);
    if (res) {
      break;
    }
  }
  return res;
}

ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
bool isLowerCase(char c) { return (c >= 'a' && c <= 'z'); }

ll powm(ll a, ll n, ll m) {
  ll ret = 1;
  while (n > 0) {
    if (n % 2 == 1) {
      ret = (ret * a) % m;
    }
    n >>= 1;
    a = (a * a) % m;
  }
  return ret;
}

const string yesno(bool ans) { return (ans ? "Yes" : "No"); }
int main() {
  int n, k;
  cin >> n >> k;
  vector<int> a(n + 1);
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < k; i++) {
    vector<int> val(n + 1, 0);
    for (int j = 0; j < n; j++) {
      int idx = j + 1;
      int l, r;
      l = max(idx - a[idx], 1);
      r = min(idx + a[idx], n);
      val[l]++;
      if (r + 1 <= n) {
        val[r + 1]--;
      }
    }
    a[0] = 0;
    for (int j = 0; j < n; j++) {
      int idx = j + 1;
      a[idx] = a[idx - 1] + val[idx];
    }
    int maxcnt = 0;
    for (int index = 0; index < n; index++) {
      int p = index + 1;
      if (a[p] == n) {
        maxcnt++;
      }
    }
    if (maxcnt == n) {
      break;
    }
  }
  for (int i = 0; i < n; i++) {
    cout << a[i + 1] << " \\n"[i == n - 1 ? 1 : 0];
  }
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;

#define all(v) v.begin(), v.end()

const ll mod = 1000000007;

ll countBits(ll in) {
  int res = 0;
  for (; in > 0; in >>= 1) {
    if ((in & 0x01) != 0) {
      res++;
    }
  }
  return res;
}

template <typename T> void show2dVector(vector<vector<T>> &v) {
  for (int i = 0; i < v.size(); i++) {
    int m = v[i].size();
    cout << i << " : ";
    for (int j = 0; i < m; i++) {
      cout << v[i][j] << " ";
    }
    cout << endl;
  }
}

void bfs(const vector<vector<int>> &g, int v, vector<bool> &seen) {
  seen[v] = true;
  cout << v << " ";
  for (auto next : g[v]) {
    if (seen[next]) {
      continue;
    }
    bfs(g, next, seen);
  }
}

bool dfs(vector<vector<int>> &g, int start, int goal, vector<bool> &seen) {
  bool res = false;
  seen[start] = true;
  if (start == goal) {
    return true;
  }
  for (auto next : g[start]) {
    if (seen[next]) {
      continue;
    }
    res = dfs(g, next, goal, seen);
    if (res) {
      break;
    }
  }
  return res;
}

ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
bool isLowerCase(char c) { return (c >= 'a' && c <= 'z'); }

ll powm(ll a, ll n, ll m) {
  ll ret = 1;
  while (n > 0) {
    if (n % 2 == 1) {
      ret = (ret * a) % m;
    }
    n >>= 1;
    a = (a * a) % m;
  }
  return ret;
}

const string yesno(bool ans) { return (ans ? "Yes" : "No"); }
int main() {
  int n, k;
  cin >> n >> k;
  vector<int> a(n + 1);
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < k; i++) {
    vector<int> val(n + 1, 0);
    for (int j = 0; j < n; j++) {
      int idx = j + 1;
      int l, r;
      l = max(idx - a[idx], 1);
      r = min(idx + a[idx], n);
      for (int index = l; index <= r; index++) {
        val[index]++;
      }
    }
    int maxcnt = 0;
    a = val;
    for (int index = 0; index < n; index++) {
      int p = index + 1;
      if (a[p] == n) {
        maxcnt++;
      }
    }
    if (maxcnt == n) {
      break;
    }
  }
  for (int i = 0; i < n; i++) {
    cout << a[i + 1] << " \\n"[i == n - 1 ? 1 : 0];
  }
  return 0;
}