Problem p02637 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <bitset>
#include <cassert>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;

// #define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int> P;
#define stop                                                                   \\
  char nyaa;                                                                   \\
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);

ll mod_pow(ll x, ll n) {
  ll res = 1;
  while (n) {
    if (n & 1)
      res = res * x % mod;
    x = x * x % mod;
    n >>= 1;
  }
  return res;
}
struct modint {
  ll n;
  modint() : n(0) { ; }
  modint(ll m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) {
  a.n += b.n;
  if (a.n >= mod)
    a.n -= mod;
  return a;
}
modint operator-=(modint &a, modint b) {
  a.n -= b.n;
  if (a.n < 0)
    a.n += mod;
  return a;
}
modint operator*=(modint &a, modint b) {
  a.n = ((ll)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
  if (n == 0)
    return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2)
    res = res * a;
  return res;
}

ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); }
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 20;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b)
    return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}

int k;
bool validarray(vector<int> &a) {
  int mi = mod, ma = 0;
  rep(i, a.size()) {
    if (a[i] < 0)
      return false;
    mi = min(mi, a[i]);
    ma = max(ma, a[i]);
  }
  return ma <= mi * 2;
}

void solve() {
  cin >> k;
  vector<int> a(k);
  rep(i, k) { cin >> a[i]; }
  if (!validarray(a)) {
    cout << -1 << "\\n";
    return;
  }
  int sum = 0;
  rep(i, k) sum += a[i];

  int las = 0;
  vector<int> ans;
  rep(i, sum) {
    vector<bool> b(k);
    for (int j = las; j < ans.size(); j++) {
      b[ans[j]] = true;
    }
    int chk = -1;
    vector<bool> b2(k);
    rep(j, k) {
      bool valid = false;
      if (b[j])
        continue;
      b2 = b;
      b2[j] = true;
      for (int ex = 0; ex <= k; ex++) {
        if (las - ex < 0)
          break;
        if (ex > 0) {
          if (b2[ans[las - ex]])
            break;
          b2[ans[las - ex]] = true;
        }

        // cout << "?! " << i << " " << j <<" "<<ex<< "\\n";
        vector<int> cop = a;

        cop[j]--;
        rep(x, k) {
          if (!b2[x])
            cop[x]--;
        }

        int mi = mod;
        rep(x, k) mi = min(mi, cop[x]);
        if (mi < 0)
          continue;

        int len = ans.size() - (las - ex);
        int fl = 0;
        bool e = false;
        rep(x, k) if (!b2[x]) {
          if (cop[x] > 2 * mi) {
            fl = len;
            cop[x]--;
            e = true;
          }
        }
        if (e)
          cop[j]--;
        else {
          if (cop[j] > 2 * mi) {
            fl = len;
            cop[j]--;
          } else {
            // cout << "hello\\n";
            rep1(t, len) {
              if (cop[ans[ans.size() - t]] > 2 * mi) {
                fl = len + 1 - t;
                break;
              }
            }
          }
        }
        rep(t, fl) cop[ans[las - ex + t]]--;
        // cout << i << " " << j << " " << ex << " " << fl << "\\n";
        if (validarray(cop)) {
          valid = true;
          break;
        }
      }
      if (valid) {
        chk = j;
        break;
      }
    }
    // cout << chk+1 << " "<<las<<"\\n";
    assert(chk >= 0);
    ans.push_back(chk);
    a[chk]--;
    if (ans.size() >= k) {
      vector<int> cnt(k, 0);
      rep(j, k) { cnt[ans[ans.size() - 1 - j]]++; }
      bool valid = true;
      rep(j, k) if (cnt[j] != 1) valid = false;
      if (valid) {
        las = ans.size();
      }
    }
  }
  rep(i, ans.size()) {
    if (i > 0)
      cout << " ";
    cout << ans[i] + 1;
  }
  cout << "\\n";
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // init();
  // int t; cin >> t; rep(i, t)
  solve();
  return 0;
}


Error: TLE

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cassert>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;

// #define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int> P;
#define stop                                                                   \\
  char nyaa;                                                                   \\
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);

ll mod_pow(ll x, ll n) {
  ll res = 1;
  while (n) {
    if (n & 1)
      res = res * x % mod;
    x = x * x % mod;
    n >>= 1;
  }
  return res;
}
struct modint {
  ll n;
  modint() : n(0) { ; }
  modint(ll m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) {
  a.n += b.n;
  if (a.n >= mod)
    a.n -= mod;
  return a;
}
modint operator-=(modint &a, modint b) {
  a.n -= b.n;
  if (a.n < 0)
    a.n += mod;
  return a;
}
modint operator*=(modint &a, modint b) {
  a.n = ((ll)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
  if (n == 0)
    return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2)
    res = res * a;
  return res;
}

ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); }
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 20;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b)
    return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}

int k;
bool validarray(vector<int> &a) {
  int mi = mod, ma = 0;
  rep(i, a.size()) {
    if (a[i] < 0)
      return false;
    mi = min(mi, a[i]);
    ma = max(ma, a[i]);
  }
  return ma <= mi * 2;
}

void solve() {
  cin >> k;
  vector<int> a(k);
  rep(i, k) { cin >> a[i]; }
  if (!validarray(a)) {
    cout << -1 << "\\n";
    return;
  }
  int sum = 0;
  rep(i, k) sum += a[i];

  int las = 0;
  vector<int> ans;
  rep(i, sum) {
    vector<bool> b(k);
    for (int j = las; j < ans.size(); j++) {
      b[ans[j]] = true;
    }
    int chk = -1;
    vector<bool> b2(k);
    rep(j, k) {
      bool valid = false;
      if (b[j])
        continue;
      b2 = b;
      b2[j] = true;
      for (int ex = 0; ex <= k; ex++) {
        if (las - ex < 0)
          break;
        if (ex > 0) {
          if (b2[ans[las - ex]])
            break;
          b2[ans[las - ex]] = true;
        }

        // cout << "?! " << i << " " << j <<" "<<ex<< "\\n";
        vector<int> cop = a;

        vector<int> cs;
        for (int loc = las - ex; loc < ans.size(); loc++)
          cs.push_back(ans[loc]);
        cs.push_back(j);
        cop[j]--;

        vector<P> v;
        rep(x, k) if (!b2[x]) { v.push_back({a[x], x}); }
        sort(all(v), greater<P>());
        for (P p : v) {
          cs.push_back(p.second);
          cop[p.second]--;
        }
        int mi = mod;
        rep(x, k) mi = min(mi, cop[x]);
        if (mi < 0)
          continue;

        int pre = 0;
        rep(x, k) {
          if (cop[cs[x]] > 2 * mi) {
            for (int y = pre; y <= x; y++) {
              cop[cs[y]]--;
            }
            pre = x + 1;
          }
        }
        if (validarray(cop)) {
          valid = true;
          break;
        }
      }
      if (valid) {
        chk = j;
        break;
      }
    }
    // cout << chk+1 << " "<<las<<"\\n";
    assert(chk >= 0);
    ans.push_back(chk);
    a[chk]--;
    if (ans.size() >= k) {
      vector<int> cnt(k, 0);
      rep(j, k) { cnt[ans[ans.size() - 1 - j]]++; }
      bool valid = true;
      rep(j, k) if (cnt[j] != 1) valid = false;
      if (valid) {
        las = ans.size();
      }
    }
  }
  rep(i, ans.size()) {
    if (i > 0)
      cout << " ";
    cout << ans[i] + 1;
  }
  cout << "\\n";
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(10);
  // init();
  // int t; cin >> t; rep(i, t)
  solve();
  return 0;
}