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

#include <bits/stdc++.h>
using namespace std;

const long long mod = 1e9 + 7;

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define ull unsigned long long
#define ld long double
#define vi vector<int>
#define vll vector<ll>
#define vc vector<char>
#define vs vector<string>
#define vpii vector<pii>
#define vpll vector<pll>

#define rep(i, n) for (int i = 0, i##_len = (n); i < i##_len; i++)
#define rep1(i, n) for (int i = 1, i##_len = (n); i <= i##_len; i++)
#define repr(i, n) for (int i = ((int)(n)-1); i >= 0; i--)
#define rep1r(i, n) for (int i = ((int)(n)); i >= 1; i--)

#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define RSORT(x) sort(rall(x));
#define pb push_back
#define mp make_pair

#define INF (1e9)
#define PI (acos(-1))
#define EPS (1e-7)

ull gcd(ull a, ull b) { return b ? gcd(b, a % b) : a; }
ull lcm(ull a, ull b) { return a / gcd(a, b) * b; }

int main() {
  int n, k;
  cin >> n >> k;
  vi a(n);
  rep(i, n) cin >> a[i];
  vi sum(n + 1);
  rep(i, n) {
    sum[max(0, i - a[i])]++;
    sum[min(n, i + a[i] + 1)]--;
  }
  rep(h, k - 1) {
    vi sum2(n + 1);
    int val = sum[0];
    sum2[0]++;
    sum2[min(n, val + 1)]--;
    bool full = (val == n);
    rep1(i, n - 1) {
      val += sum[i];
      sum2[max(0, i - val)]++;
      sum2[min(n, i + val + 1)]--;
      if (i <= n - 1 && val != n)
        full = false;
    }
    swap(sum, sum2);
    if (full)
      break;
  }
  vi ans(n);
  ans[0] = sum[0];
  rep1(i, n - 1) ans[i] = ans[i - 1] + sum[i];
  rep(i, n) printf("%d%c", ans[i], (i < n - 1 ? ' ' : '\\n'));
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;

const long long mod = 1e9 + 7;

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define ull unsigned long long
#define ld long double
#define vi vector<int>
#define vll vector<ll>
#define vc vector<char>
#define vs vector<string>
#define vpii vector<pii>
#define vpll vector<pll>

#define rep(i, n) for (int i = 0, i##_len = (n); i < i##_len; i++)
#define rep1(i, n) for (int i = 1, i##_len = (n); i <= i##_len; i++)
#define repr(i, n) for (int i = ((int)(n)-1); i >= 0; i--)
#define rep1r(i, n) for (int i = ((int)(n)); i >= 1; i--)

#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define RSORT(x) sort(rall(x));
#define pb push_back
#define mp make_pair

#define INF (1e9)
#define PI (acos(-1))
#define EPS (1e-7)

ull gcd(ull a, ull b) { return b ? gcd(b, a % b) : a; }
ull lcm(ull a, ull b) { return a / gcd(a, b) * b; }

int main() {
  int n, k;
  cin >> n >> k;
  vi a(n);
  rep(i, n) cin >> a[i];
  vi sum(n + 1);
  rep(i, n) {
    sum[max(0, i - a[i])]++;
    sum[min(n, i + a[i] + 1)]--;
  }
  rep(h, k - 1) {
    vi sum2(n + 1);
    int val = sum[0];
    sum2[0]++;
    sum2[min(n, val + 1)]--;
    bool full = (val == n);
    rep1(i, n - 1) {
      val += sum[i];
      sum2[max(0, i - val)]++;
      sum2[min(n, i + val + 1)]--;
      if (i < n - 1 && val != 0)
        full = false;
    }
    swap(sum, sum2);
    if (full)
      break;
  }
  vi ans(n);
  ans[0] = sum[0];
  rep1(i, n - 1) ans[i] = ans[i - 1] + sum[i];
  rep(i, n) printf("%d%c", ans[i], (i < n - 1 ? ' ' : '\\n'));
  return 0;
}