Submission #991318

#	Time	Username	Problem	Language	Result	Execution time	Memory
991318		12345678	Meetings 2 (JOI21_meetings2)	C++17	100 / 100	212 ms	27220 KiB

meetings2

#include <bits/stdc++.h>

using namespace std;

const int nx=2e5+5;

int n, u, v, sz[nx], lvl[nx], mx[nx], res[nx], used[nx];
vector<int> d[nx];
pair<int, int> dp[nx];

void dfs(int u, int p)
{
    lvl[u]=lvl[p]+1;
    sz[u]=1;
    for (auto v:d[u]) if (v!=p&&!used[v]) dfs(v, u), sz[u]+=sz[v];
    mx[sz[u]]=max(mx[sz[u]], lvl[u]);
}

int dfssz(int u, int p)
{
    sz[u]=1;
    for (auto v:d[u]) if (v!=p&&!used[v]) sz[u]+=dfssz(v, u);
    return sz[u];
}

int findcentroid(int u, int p, int rtsz)
{
    for (auto v:d[u]) if (v!=p&&!used[v]&&2*sz[v]>rtsz) return findcentroid(v, u, rtsz);
    return u;
}

void decomposition(int u)
{
    u=findcentroid(u, u, dfssz(u, u));
    used[u]=1;
    int sm=sz[u];
    for (int i=1; i<=sm; i++) dp[i]={-1, -1};
    for (auto v:d[u])
    {
        if (used[v]) continue;
        lvl[v]=0;
        dfs(v, v);
        for (int i=sz[v]; i>=1; i--) 
        {
            mx[i]=max(mx[i], mx[i+1]);
            //cout<<"mx "<<v<<' '<<u<<' '<<i<<' '<<mx[i]<<'\n';
            if (mx[i]==0) continue;
            if (dp[i].first==-1||dp[i].first<mx[i]) swap(dp[i].first, dp[i].second), dp[i].first=mx[i];
            else if (dp[i].second==-1||mx[i]>dp[i].second) dp[i].second=mx[i];
        }
        for (int i=1; i<=sz[v]; i++) mx[i]=0;
    }
    for (int i=1; i<=sm; i++)
    {
        //cout<<"debug "<<u<<' '<<i<<' '<<dp[i].first<<' '<<dp[i].second<<'\n';
        if (dp[i].first!=-1&&dp[i].second==-1) res[i]=max(res[i], dp[i].first);
        else if (dp[i].first!=-1&&dp[i].second!=-1) res[i]=max(res[i], dp[i].first+dp[i].second);
    }
    for (auto v:d[u]) if (!used[v]) decomposition(v);
}

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n;
    for (int i=1; i<n; i++) cin>>u>>v, d[u].push_back(v), d[v].push_back(u);
    decomposition(1);
    for (int i=1; i<=n; i++) cout<<((i%2)?1:(res[i/2]+1))<<'\n';
}

• Subtask 1: 4 / 4
• Subtask 2: 16 / 16
• Subtask 3: 80 / 80