Submission #531073

#	Time	Username	Problem	Language	Result	Execution time	Memory
531073		Alex_tz307	Synchronization (JOI13_synchronization)	C++17	100 / 100	238 ms	24784 KiB

synchronization

#include <bits/stdc++.h>

using namespace std;

const int kN = 1e5;
const int kLog = 16;
int n, m, q, timer, tin[1 + kN], tout[1 + kN], aib[1 + kN], card[1 + kN], last[1 + kN], anc[1 + kN][1 + kLog];
short act[1 + kN];
vector<int> g[1 + kN];
pair<int, int> edges[1 + kN];

void dfs(int u) {
  tin[u] = ++timer;
  card[u] = 1;
  act[u] = -1;
  for (int i = 1; i <= kLog; ++i) {
    anc[u][i] = anc[anc[u][i - 1]][i - 1];
    if (anc[u][i] == 0) {
      break;
    }
  }
  for (int v : g[u]) {
    if (v != anc[u][0]) {
      anc[v][0] = u;
      dfs(v);
    }
  }
  tout[u] = timer;
}

void update(int x, int v) {
  for (int i = x; i <= n; i += i & -i) {
    aib[i] += v;
  }
}

int query(int x) {
  int ans = 0;
  for (int i = x; i > 0; i = i & (i - 1)) {
    ans += aib[i];
  }
  return ans;
}

int findRoot(int v) {
  for (int i = kLog; i >= 0; --i) {
    if (anc[v][i] && query(tin[v]) == query(tin[anc[v][i]])) {
      v = anc[v][i];
    }
  }
  return v;
}

void testCase() {
  cin >> n >> m >> q;
  for (int i = 1; i < n; ++i) {
    int u, v;
    cin >> u >> v;
    g[u].emplace_back(v);
    g[v].emplace_back(u);
    edges[i] = {u, v};
  }
  dfs(1);
  for (int v = 2; v <= n; ++v) {
    update(tin[v], act[v]);
    update(tout[v] + 1, -act[v]);
  }
  for (int i = 0; i < m; ++i) {
    int d;
    cin >> d;
    int u, v;
    tie(u, v) = edges[d];
    if (anc[u][0] == v) {
      swap(u, v);
    }
    act[v] *= -1;
    if (act[v] == 1) {
      int rootU = findRoot(u);
      card[rootU] += card[v] - last[v];
    } else {
      card[v] = card[findRoot(u)];
      last[v] = card[v];
    }
    update(tin[v], act[v]);
    update(tout[v] + 1, -act[v]);
  }
  for (int i = 0; i < q; ++i) {
    int v;
    cin >> v;
    cout << card[findRoot(v)] << '\n';
  }
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int tests = 1;
  for (int tc = 0; tc < tests; ++tc) {
    testCase();
  }
  return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 10 / 10
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40