Submission #577945

#	Time	Username	Problem	Language	Result	Execution time	Memory
577945		Huy	Synchronization (JOI13_synchronization)	C++17	100 / 100	560 ms	27796 KiB

synchronization

#include<bits/stdc++.h>
//#define int long long
#define pii pair<ll,ll>
#define fi first
#define se second

using namespace std;
using ll = long long;
using ldb = long double;
const int N = (int)5e5+2;
const int maxN = (int)2e5 + 5;
const int mod = 1e9 + 7;
const ll infty = 1e18;

void InputFile()
{
    //freopen("scrivener.inp","r",stdin);
    //freopen("scrivener.out","w",stdout);
    //freopen("test.out","r",stdin);
}

void FastInput()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

int n,m,q;
vector<vector<int>> adj;
int anc[25][maxN];
int lg[maxN];
int depth[maxN];
int TimeDFS = 0;
int sta[maxN];
int fin[maxN];
int now[maxN];
int lst[maxN];
int x[maxN],y[maxN];
int apr[maxN];

void Prepare()
{
    lg[1] = 0;
    for(int i = 2;i < maxN;i++)
    {
        lg[i] = lg[i/2] + 1;
    }
}

void Read()
{
    cin >> n >> m >> q;
    adj.resize(n+1);
    for(int i = 1;i < n;i++)
    {
        int u,v;
        cin >> u >> v;
        x[i] = u;
        y[i] = v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
}

int bit[maxN];

void Update(int idx,int val)
{
    while(idx <= n)
    {
        bit[idx] += val;
        idx += (idx & (-idx));
    }
}

void UpdRange(int l,int r,int val)
{
    Update(l,val);
    Update(r+1,-val);
}

int Get(int idx)
{
    if(idx == 0) return -1;
    int res = 0;
    while(idx > 0)
    {
        res += bit[idx];
        idx -= (idx & (-idx));
    }
    return res;
}

void preDFS(int u,int p)
{
    sta[u] = ++TimeDFS;
    UpdRange(sta[u],sta[u],depth[u]+1);
    now[u] = 1;
    lst[u] = 0;
    for(int v : adj[u])
    {
        if(v == p) continue;
        depth[v] = depth[u] + 1;
        anc[0][v] = u;
        for(int i = 1;i <= lg[n];i++)
        {
            anc[i][v] = anc[i-1][anc[i-1][v]];
        }
        preDFS(v,u);
    }
    fin[u] = TimeDFS;
}

int Find(int u)
{
    int comp = Get(sta[u]);
    for(int i = lg[n];i >= 0;i--)
    {
        if(Get(sta[anc[i][u]]) == Get(sta[u])) u = anc[i][u];
    }
    return u;
}

void Solve()
{
    Prepare();
    preDFS(1,0);
    for(int i = 1;i <= m;i++)
    {
        int edg_id;
        cin >> edg_id;
        if(depth[x[edg_id]] > depth[y[edg_id]])
        {
            swap(x[edg_id],y[edg_id]);
        }
        apr[edg_id]++;
        if(apr[edg_id]%2)
        {
            UpdRange(sta[y[edg_id]],fin[y[edg_id]],-1);
            int par = Find(y[edg_id]);
            now[par] += now[y[edg_id]] - lst[y[edg_id]];
            now[y[edg_id]] = lst[y[edg_id]] = now[par];
        }
        else
        {
            int par = Find(y[edg_id]);
            //now[par] += now[y[edg_id]] - lst[y[edg_id]];
            now[y[edg_id]] = lst[y[edg_id]] = now[par];
            UpdRange(sta[y[edg_id]],fin[y[edg_id]],1);
        }
    }
    //cout << sta[2] <<' '<< fin[2];return;
    //cout << Get(sta[3]);return;
    while(q--)
    {
        int u;
        cin >> u;
        int par = Find(u);
        cout << now[par] <<'\n';
    }
}

void Debug()
{
    //Main_sub();
    //Naive();
}


int32_t main()
{
    FastInput();
    //InputFile();
    //int sub_type;
    //cin >> sub_type;
    //Sieve();
    int test;
    //cin >> test;
    test = 1;
    while(test--)
        //for(int prc = 1; prc <= test; prc++)
    {
        Read();
        Solve();
        //Debug();
    }
}

/*
13 1
769 514 336 173 181 373 519 338 985 709 729 702 168
12 581
*/

Compilation message (stderr)

synchronization.cpp: In function 'int Find(int)':
synchronization.cpp:116:9: warning: unused variable 'comp' [-Wunused-variable]
  116 |     int comp = Get(sta[u]);
      |         ^~~~

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