Submission #998354

#	Time	Username	Problem	Language	Result	Execution time	Memory
998354		fuad27	Synchronization (JOI13_synchronization)	C++17	100 / 100	362 ms	26592 KiB

synchronization

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+10;
const int lg = 20;
int tin[N], tout[N];
int up[N][lg];
pair<int,int> e[N];
vector<int> child[N];
int tim=0;
array<int, 2> ans[N];
int depth[N];
namespace BIT {
  int fen[N];
  void upd(int at, int val) {
    at++;
    while(at < N) {
      fen[at] += val;
      at += at&-at;
    }
  }
  int query(int at) {
    at++;
    int ret = 0;
    while(at > 0) {
      ret += fen[at];
      at -= at&-at;
    }
    return ret;
  }
};
void change(int at, int val) {
  BIT::upd(tin[at], val);
  BIT::upd(tout[at], -val);
}
int query(int anc, int ch) {
  return BIT::query(tin[ch])-BIT::query(tin[anc]);
}
void dfs(int at, int p) {
  up[at][0] = p;
  tin[at] = tim++;
  for(int i = 1;i<lg;i++) {
    up[at][i] = up[up[at][i-1]][i-1];
  }
  for(int i = 0;i<child[at].size();i++) {
    if(child[at][i] != p) {
      depth[child[at][i]] = depth[at]+1;
      dfs(child[at][i], at);
    }
  }
  tout[at] = tim;
}
int findroot(int at) {
  for(int i = lg-1;i>=0;i--) {
    if(up[at][i] == 0)continue;
    if(query(up[at][i], at) == depth[at]-depth[up[at][i]]) {
      at = up[at][i];
    }
  }
  return at;
}
int state[N];
int main () {
  int n, m, q;
  cin >> n >> m >> q;
  memset(up, 0, sizeof up);  
  for(int i = 1;i<n;i++) {
    cin >> e[i].first >> e[i].second;
    child[e[i].first].push_back(e[i].second);
    child[e[i].second].push_back(e[i].first);
  }
  dfs(1, 0);
  for(int i = 1;i<n;i++) {
    if(depth[e[i].first]>depth[e[i].second])swap(e[i].first, e[i].second);
  }
  for(int i = 1;i<=n;i++)ans[i][0]=1;
  for(int i = 0;i<m;i++) {
    int c;
    cin >> c;
    state[c]^=1;
    if(state[c] == 1) {
      int r = findroot(e[c].first);
      int v1 = ans[e[c].second][0]+ans[r][0]-ans[e[c].second][1];
      change(e[c].second, 1);
      ans[r][0] = v1;
    }
    else {
      int r = findroot(e[c].second);
      ans[e[c].second][1] = ans[r][0];
      ans[e[c].second][0] = ans[r][0];
      change(e[c].second, -1);
    }
  }
  while(q--) {
    int c;
    cin >> c;
    cout << ans[findroot(c)][0] << "\n";
  }
}

Compilation message (stderr)

synchronization.cpp: In function 'void dfs(int, int)':
synchronization.cpp:44:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |   for(int i = 0;i<child[at].size();i++) {
      |                 ~^~~~~~~~~~~~~~~~~

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