Problem p02585 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define pli pair<ll, int>
#define pil pair<int, ll>
#define pll pair<ll, ll>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep3(i, l, n) for (int i = l; i < (n); ++i)
#define sz(v) (int)v.size()
#define endl '\\n'
const int inf = 1000000007;
const ll INF = 1e18;
// int mod = 998244353;
int mod = 1000000007;
const double eps = 1e-8;
#define abs(x) (x >= 0 ? x : -(x))
#define lb(v, x) (int)(lower_bound(all(v), x) - v.begin())
#define ub(v, x) (int)(upper_bound(all(v), x) - v.begin())
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
template <typename T, typename U> T pow_(T a, U b) {
  return b ? pow_(a * a, b / 2) * (b % 2 ? a : 1) : 1;
}
ll modpow(ll a, ll b, ll _mod) {
  return b ? modpow(a * a % _mod, b / 2, _mod) * (b % 2 ? a : 1) % _mod : 1;
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << p.F << " " << p.S;
  return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  rep(i, sz(vec)) {
    if (i)
      os << " ";
    os << vec[i];
  }
  return os;
}
template <class T> ostream &operator<<(ostream &os, const set<T> &s) {
  for (auto si : s)
    os << si << " ";
  return os;
}
template <typename T> inline istream &operator>>(istream &is, vector<T> &v) {
  rep(j, sz(v)) is >> v[j];
  return is;
}
template <class T, class T2> inline void add(T &a, T2 b) {
  a += b % mod;
  if (a >= mod)
    a -= mod;
}
template <class T> void operator+=(vector<T> &v, vector<T> v2) {
  rep(i, sz(v2)) v.eb(v2[i]);
}

void solve();

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << fixed << setprecision(12); // debuged
  int T;
  T = 1;
  while (T--)
    solve();
}

// https://atcoder.jp/contests/abc175/submissions/15967390
// vに入れる順番がおかしい
void solve() {
  int n, k;
  cin >> n >> k;
  vector<int> p(n), c(n);
  cin >> p >> c;
  rep(i, n)-- p[i];

  vector<int> visited(n, -1);
  vector<vector<int>> v(n);
  rep(i, n) { // O(N)
    if (visited[i] != -1)
      continue;
    int now = i;
    while (1) {
      visited[now] = i;
      v[i].eb(c[now]);

      now = p[now];
      if (visited[now] != -1)
        break;
    }
  }
  // cerr << "vis " << visited << endl;

  ll ans = *max_element(all(c));
  if (ans <= 0) {
    cout << ans << endl;
    return;
  }

  rep(i, n) {
    if (sz(v[i]) == 0)
      continue;
    ll sum = accumulate(all(v[i]), 0LL);
    // cerr << v[i] << "  " << sum << endl;

    // 長さ2倍にして, 取る連続区間を探索
    int sz_ = sz(v[i]);
    rep(j, sz_) v[i].eb(v[i][j]);
    rep(j, sz(v[i])) {
      ll sum_ = 0;
      // cerr << j << " " << k << " " << sz(v[i]) / 2 << endl;
      rep3(l, j, j + min(k, sz_)) {
        if (l == sz(v[i]))
          break;
        sum_ += v[i][l];
        if (sum > 0)
          chmax(ans, sum_ + max(0, k - (l - j + 1)) / sz_ * sum);
        chmax(ans, sum_);
      }
    }
  }
  cout << ans << endl;
}


Error: 0

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define pli pair<ll, int>
#define pil pair<int, ll>
#define pll pair<ll, ll>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep3(i, l, n) for (int i = l; i < (n); ++i)
#define sz(v) (int)v.size()
#define endl '\\n'
const int inf = 1000000007;
const ll INF = 1e18;
// int mod = 998244353;
int mod = 1000000007;
const double eps = 1e-8;
#define abs(x) (x >= 0 ? x : -(x))
#define lb(v, x) (int)(lower_bound(all(v), x) - v.begin())
#define ub(v, x) (int)(upper_bound(all(v), x) - v.begin())
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
template <typename T, typename U> T pow_(T a, U b) {
  return b ? pow_(a * a, b / 2) * (b % 2 ? a : 1) : 1;
}
ll modpow(ll a, ll b, ll _mod) {
  return b ? modpow(a * a % _mod, b / 2, _mod) * (b % 2 ? a : 1) % _mod : 1;
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << p.F << " " << p.S;
  return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  rep(i, sz(vec)) {
    if (i)
      os << " ";
    os << vec[i];
  }
  return os;
}
template <class T> ostream &operator<<(ostream &os, const set<T> &s) {
  for (auto si : s)
    os << si << " ";
  return os;
}
template <typename T> inline istream &operator>>(istream &is, vector<T> &v) {
  rep(j, sz(v)) is >> v[j];
  return is;
}
template <class T, class T2> inline void add(T &a, T2 b) {
  a += b % mod;
  if (a >= mod)
    a -= mod;
}
template <class T> void operator+=(vector<T> &v, vector<T> v2) {
  rep(i, sz(v2)) v.eb(v2[i]);
}

void solve();

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << fixed << setprecision(12); // debuged
  int T;
  T = 1;
  while (T--)
    solve();
}

void solve() {
  int n, k;
  cin >> n >> k;
  vector<int> p(n), c(n);
  cin >> p >> c;
  rep(i, n)-- p[i];

  vector<int> visited(n, -1);
  rep(i, n) { // O(N)
    if (visited[i] != -1)
      continue;
    int now = i;
    visited[now] = i;
    while (1) {
      now = p[now];
      if (visited[now] != -1)
        break;
      visited[now] = i;
    }
  }
  // cerr << "vis " << visited << endl;
  rep(i, n) if (visited[i] < 0 || visited[i] >= n) while (1) {}

  vector<vector<int>> v(n);
  rep(i, n) v[visited[i]].eb(c[i]);

  ll ans = *max_element(all(c));
  if (ans <= 0) {
    cout << ans << endl;
    return;
  }

  rep(i, n) {
    if (sz(v[i]) == 0)
      continue;
    // cerr << "v " << v[i] << endl;
    ll round = accumulate(all(v[i]), 0LL);
    // cerr << "round " << round << endl;

    rep(loop, 2) {
      int k2 = k;
      ll sum = 0;
      if (round > 0 && sz(v[i]) <= k) {
        sum += k / sz(v[i]) * round; // 10^9 / 10^4 * 10^13
        k2 %= sz(v[i]);
        if (loop == 1) {
          // 1回分除く
          sum -= round;
          k2 += sz(v[i]);
        }
      }

      // 負を跨いだ方がいい場合も
      vector<vector<ll>> dp(2, vector<ll>(k2 + 2, -INF));
      dp[1][1] = v[i][0];
      rep(j, sz(v[i])) {
        rep(l, k2 + 1) {
          chmax(dp[1][l], dp[0][l]); // 加えない
          chmax(dp[1][l + 1], dp[0][l] + v[i][j]);
        }
        dp[0] = dp[1];
        rep(l, k2 + 2) dp[1][l] = -INF;
      }
      ll ma = -INF;
      rep3(j, 1, k2 + 1) chmax(ma, dp[0][j]);
      if (k != k2)
        chmax(ma, 0);
      chmax(ans, sum + ma);
    }
  }
  cout << ans << endl;
}