Submission #587403

#	Time	Username	Problem	Language	Result	Execution time	Memory
587403		MilosMilutinovic	Spring cleaning (CEOI20_cleaning)	C++14	100 / 100	372 ms	38832 KiB

cleaning

/**
 *    author:  wxhtzdy
 *    created: 01.07.2022 19:07:12
**/
#include <bits/stdc++.h>

using namespace std;

string to_string(string s) {
  return '"' + s + '"';
}
string to_string(const char* s) {
  return to_string((string) s);
}
string to_string(bool b) {
  return (b ? "true" : "false");
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);  
  int n, q;
  cin >> n >> q;
  const int MAX = 200000;
  vector<vector<int>> g(MAX);
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    cin >> u >> v;
    --u; --v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  vector<int> cnt(n);
  int ans = 0;  
  const int L = 20;
  vector<vector<int>> jump(n, vector<int>(L));
  vector<int> dep(n);
  vector<int> tin(n);
  int T = 0;
  function<void(int, int)> Dfs = [&](int v, int pr) {
    tin[v] = ++T; 
    dep[v] = dep[pr] + 1;
    jump[v][0] = pr;
    if ((int) g[v].size() <= 1) {
      cnt[v] += 1;
    }
    for (int u : g[v]) {
      if (u != pr) {
        Dfs(u, v);
        cnt[v] += cnt[u];
      }
    }
    if (pr != v) {
      ans += 2 - (cnt[v] % 2);
    }
  };                   
  int root;
  for (int i = 0; i < n; i++) {
    if ((int) g[i].size() > 1) {
      root = i;
    }
  }
  Dfs(root, root);
  for (int j = 1; j < L; j++) {
    for (int i = 0; i < n; i++) {
      jump[i][j] = jump[jump[i][j - 1]][j - 1];
    }
  }
  auto LCA = [&](int v, int u) {
    if (dep[u] > dep[v]) {
      swap(u, v);
    }
    for (int i = L - 1; i >= 0; i--) {
      if (dep[jump[v][i]] >= dep[u]) {
        v = jump[v][i];
      }
    }
    for (int i = L - 1; i >= 0; i--) {
      if (jump[u][i] != jump[v][i]) {
        u = jump[u][i];
        v = jump[v][i];
      }
    }
    return u == v ? v : jump[v][0];
  };                   
  vector<vector<int>> cc(n, vector<int>(2));
  Dfs = [&](int v, int pr) {
    cc[v] = cc[pr];
    cc[v][cnt[v] % 2] += 1;
    for (int u : g[v]) {
      if (u != pr) {
        Dfs(u, v);
      }
    }
  };                   
  Dfs(root, root);
  int tot = 0;
  for (int i = 0; i < n; i++) {
    if ((int) g[i].size() <= 1) {
      tot += 1;
    }
  }                
  vector<int> par(MAX);
  vector<int> sub(MAX);
  while (q--) {
    int d;
    cin >> d;
    vector<int> a(d);      
    for (int i = 0; i < d; i++) {
      cin >> a[i];
      --a[i];
    }
    sort(a.begin(), a.end(), [&](int i, int j) {
      return tin[i] < tin[j];
    });
    int ntot = tot + d;
    for (int i = 0; i < d; i++) {
      if (i == 0 || a[i] != a[i - 1]) {
        if ((int) g[a[i]].size() == 1) {
          ntot -= 1;
          sub[a[i]] -= 1;
        }
      }
    }
    vector<int> xs(1, root);
    for (int i = 0; i < d; i++) {
      xs.push_back(a[i]);
      if (i > 0) {
        xs.push_back(LCA(a[i], a[i - 1]));
      }
    }
    sort(xs.begin(), xs.end());
    xs.erase(unique(xs.begin(), xs.end()), xs.end());
    sort(xs.begin(), xs.end(), [&](int i, int j) {
      return tin[i] < tin[j];
    });
    vector<int> stk(1, root);
    for (int i = 0; i < (int) xs.size(); i++) {
      while (!stk.empty() && LCA(stk.back(), xs[i]) != stk.back()) {
        stk.pop_back();
      }
      par[xs[i]] = stk.back();
      stk.push_back(xs[i]);
    }
    for (int i = 0; i < d; i++) {
      sub[a[i]] += 1;
    }
    for (int i = (int) xs.size() - 1; i >= 0; i--) {
      if (xs[i] != root) {
        sub[par[xs[i]]] += sub[xs[i]];
      }
    }
    int nans = ans + d; 
    for (int i = 0; i < (int) xs.size(); i++) {
      if (sub[xs[i]] % 2 == 1) {
        int c0 = cc[xs[i]][0] - cc[par[xs[i]]][0];
        int c1 = cc[xs[i]][1] - cc[par[xs[i]]][1];
        nans -= c0;
        nans += c1;
      }
    }
    if (ntot % 2 == 0) {
      cout << nans << '\n';
    } else {
      cout << -1 << '\n';
    }
    for (int i : xs) {
      sub[i] = 0;
    }
  }                                                                  
  return 0;
}

Compilation message (stderr)

cleaning.cpp: In function 'int main()':
cleaning.cpp:178:7: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
  178 |       if (xs[i] != root) {
      |       ^~

• Subtask 1: 0 / 0
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 17 / 17
• Subtask 7: 30 / 30