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Submission #595626

# Submission time Handle Problem Language Result Execution time Memory
595626 2022-07-13T22:10:30 Z czhang2718 Meetings 2 (JOI21_meetings2) C++17
0 / 100
 4 ms 5032 KB 
#include "bits/stdc++.h"
using namespace std;

const int N=2e5+1;
int n;
vector<int> adj[N];
int ans[N];
bool vis[N];
int sz[N];

void dfs1(int x, vector<int> &nodes){
    vis[x]=1;
    nodes.push_back(x);
    sz[x]=1;
    for(int k:adj[x]){
        if(vis[k]) continue;
        dfs1(k, nodes);
        sz[x]+=sz[k];
    }
}

void dfs2(int x, int cnt, int &c){
    vis[x]=1;
    bool found=0;
    for(int k:adj[x]){
        if(vis[k]) continue;
        if(sz[k]>cnt/2){
            dfs2(k, cnt, c);
            if(c) return;
        }
    }
    if(!c) c=x;
}

void dfs3(int x, vector<int>& dp, int d){
    sz[x]=1;
    vis[x]=1;
    for(int k:adj[x]){
        if(vis[k]) continue;
        dfs3(k, dp, d+1);
        sz[x]+=sz[k];
    }
    if(dp.size()<=sz[x]) dp.resize(sz[x]+1);
    // cout << x << " dp[" << sz[x] << "] max= " << d << "\n";
    dp[sz[x]]=max(dp[sz[x]], d);
}

void go(int x){
    // cout << "go " << x << "\n";
    vector<int> nodes;
    dfs1(x, nodes);
    if(nodes.size()<=2) return;
    for(int u:nodes) vis[u]=0;

    int c=0;
    dfs2(x, nodes.size(), c);
    // cout << "nodes ";
    // for(int x:nodes) cout << x << vis[x] << " ";
    // cout << "\ncentroid: " << c << "\n";

    for(int u:nodes) if(u!=c) vis[u]=0;
    for(int k:adj[c]) if(!vis[k]) go(k);

    vector<int> mx(nodes.size()), mx2(nodes.size());

    for(int u:nodes) if(u!=c) vis[u]=0;
    for(int k:adj[c]){
        if(vis[k]) continue;
        vector<int> dp;
        dfs3(k, dp, 1);

        for(int i=dp.size()-1; i; i--){
            assert(dp.size()<=nodes.size());
            if(i!=dp.size()-1) dp[i]=max(dp[i], dp[i+1]);
            if(dp[i]>mx[i]) mx2[i]=mx[i], mx[i]=dp[i];
            else if(dp[i]>mx2[i]) mx2[i]=dp[i];
            // cout << mx[i] << mx2[i] << "\n";
        }
    }

    for(int i=1; i<min(n/2+1, (int)nodes.size()); i++){
        if(mx[i] && mx2[i]) ans[2*i]=max(ans[2*i], mx[i]+mx2[i]);
    }
}

int main(){
    cin.tie(0)->sync_with_stdio(0);

    cin >> n;
    for(int i=1; i<n; i++){
        int u,v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    go(1);

    for(int i=1; i<=n; i++){
        if(i&1) cout << "1\n";
        else cout << max(2, ans[i]+1) << "\n";
    }
}

Compilation message

meetings2.cpp: In function 'void dfs2(int, int, int&)':
meetings2.cpp:24:10: warning: unused variable 'found' [-Wunused-variable]
   24 |     bool found=0;
      |          ^~~~~
meetings2.cpp: In function 'void dfs3(int, std::vector<int>&, int)':
meetings2.cpp:43:17: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   43 |     if(dp.size()<=sz[x]) dp.resize(sz[x]+1);
      |        ~~~~~~~~~^~~~~~~
meetings2.cpp: In function 'void go(int)':
meetings2.cpp:74:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   74 |             if(i!=dp.size()-1) dp[i]=max(dp[i], dp[i+1]);
      |                ~^~~~~~~~~~~~~

Subtask #1
0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 2 ms 5032 KB Output is correct
3 Correct 4 ms 5016 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Incorrect 3 ms 4948 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #2
0 / 16.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 2 ms 5032 KB Output is correct
3 Correct 4 ms 5016 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Incorrect 3 ms 4948 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #3
0 / 80.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 2 ms 5032 KB Output is correct
3 Correct 4 ms 5016 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Incorrect 3 ms 4948 KB Output isn't correct
6 Halted 0 ms 0 KB -