Submission #1211311

#	Time	Username	Problem	Language	Result	Execution time	Memory
1211311		guagua0407	Meetings 2 (JOI21_meetings2)	C++20	100 / 100	239 ms	38036 KiB

meetings2

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

const int mxn=2e5+5;
vector<int> adj[mxn];
int up[mxn][20];
int depth[mxn];
int sz[mxn];

int dfs(int v,int p=0){
    sz[v]=1;
    up[v][0]=p;
    depth[v]=depth[p]+1;
    for(auto u:adj[v]){
        if(u==p) continue;
        sz[v]+=dfs(u,v);
    }
    return sz[v];
}

int find(int v,int p,int tot){
    for(auto u:adj[v]){
        if(u==p) continue;
        if(sz[u]*2>=tot) return find(u,v,tot);
    }
    return v;
}

int dis(int a,int b){
    if(depth[a]<depth[b]) swap(a,b);
    int len=depth[a]-depth[b];
    int ans=0;
    for(int i=0;i<20;i++){
        if(len&(1<<i)){
            ans+=(1<<i);
            a=up[a][i];
        }
    }
    if(a==b) return ans;
    for(int i=19;i>=0;i--){
        int ta=up[a][i];
        int tb=up[b][i];
        if(ta!=tb){
            ans+=(1<<i)*2;
            a=ta;
            b=tb;
        }
    }
    return ans+2;
}

int main(){_
    int n;
    cin>>n;
    for(int i=0;i<n-1;i++){
        int a,b;
        cin>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    dfs(1);
    int root=find(1,0,n);
    dfs(root);
    for(int j=1;j<20;j++){
        for(int i=1;i<=n;i++){
            up[i][j]=up[up[i][j-1]][j-1];
        }
    }
    int A=root;
    int B=root;
    int cur=0;
    vector<int> ord;
    for(int i=1;i<=n;i++){
        if(i==root) continue;
        ord.push_back(i);
    }
    auto comp=[&](int a,int b){
        return sz[a]>sz[b];
    };
    sort(all(ord),comp);
    vector<int> ans(n+1);
    //cout<<root<<'\n';
    for(auto v:ord){
        int aa=dis(v,A);
        int bb=dis(v,B);
        //cout<<v<<' '<<A<<' '<<B<<' '<<aa<<' '<<bb<<'\n';
        ans[sz[v]]=max(ans[sz[v]],max(aa,bb));
        if(aa<bb){
            swap(aa,bb);
            swap(A,B);
        }
        if(aa>cur){
            B=v;
            cur=aa;
        }
    }
    for(int i=n-1;i>=1;i--){
        ans[i]=max(ans[i],ans[i+1]);
    }
    for(int i=1;i<=n;i++){
        if(i%2==1) cout<<1<<'\n';
        else cout<<ans[i/2]+1<<'\n';
    }
    return 0;
}
//maybe its multiset not set
//yeeorz
//diaoborz

Compilation message (stderr)

meetings2.cpp: In function 'void setIO(std::string)':
meetings2.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
meetings2.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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