Submission #844818

#	Time	Username	Problem	Language	Result	Execution time	Memory
844818		Cookie	Meetings 2 (JOI21_meetings2)	C++14	100 / 100	235 ms	51108 KiB

meetings2

#include<bits/stdc++.h>
#define ll long long
#define vt vector
#define pb push_back
#define pii pair<int, int>
#define sz(v) (int)v.size()
using namespace std;
const ll base = 107, mod = 1e9 + 7;
const int mxn = 2e5 + 5, inf = 1e9, sq = 400;
int n;
vt<int>adj[mxn + 1];
int dep[mxn + 1], up[mxn + 1][18], ans[mxn + 1], sz[mxn + 1];

int dfs_sz(int s, int pre){
    sz[s] = 1;
    for(auto i: adj[s]){
        if(i != pre){
            sz[s] += dfs_sz(i, s);
        }
    }
    return(sz[s]);
}
pii centroid(int s, int pre, int need){
    pii cand = make_pair(n, s);
    int mxsub = 0;
    for(auto i: adj[s]){
        if(i != pre){
            cand = min(cand, centroid(i, s, need));
            mxsub = max(mxsub, sz[i]);
        }
    }
    mxsub = max(mxsub, need - sz[s]);
    cand = min(cand, make_pair(mxsub, s));
    return(cand);
}
void dfs_lca(int s, int pre){
    for(auto i: adj[s]){
        if(i != pre){
           
            dep[i] = dep[s] + 1; up[i][0] = s;
            dfs_lca(i, s);
        }
    }
}
 
int lca(int u, int v){
    if(dep[u] < dep[v])swap(u, v);
    int k = dep[u] - dep[v];
    for(int i = 0; i < 18; i++){
        if(k & (1 << i)){
            u = up[u][i]; 
        }
    }
    if(u == v)return(u);
    //cout << u << " " << v << " ";
    for(int i = 17; i >= 0; i--){
        if(up[u][i] != up[v][i]){
            u = up[u][i]; v = up[v][i];
        }
    }
    //cout << u << " " << v << " ";
    return(up[u][0]);
}
int dist(int u, int v){
    return(dep[u] + dep[v] - 2 * dep[lca(u, v)]);
}
vt<int>events[mxn + 1];
int main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> n;
    for(int i = 1; i < n; i++){
        int u, v; cin >> u >> v;
        adj[u].pb(v); adj[v].pb(u);
    }
    int c = centroid(1, -1, dfs_sz(1, -1)).second;
   
    dfs_sz(c, -1);
    dfs_lca(c, -1);
    
    for(int i = 1; i < 18; i++){
        for(int j = 1; j <= n; j++){
            up[j][i] = up[up[j][i - 1]][i - 1];
        }
    }
    
    //cout << up[10][0];
    int ld = c, rd = c, len = 0;
    for(int i = 1; i <= n; i++){
        
        events[sz[i]].pb(i);
    }
    
    for(int i = n / 2; i >= 1; i--){
        for(auto u: events[i]){
            //sz[u] will always be the minimum :))
            //cout << u << " ";
            int expand_rght = dist(ld, u), expand_lft = dist(u, rd);
            if(expand_rght > len){
                len = expand_rght; rd = u;
            }else if(expand_lft > len){
                len = expand_lft; ld = u;
            }
        }
        //cout << ld << " " << rd << " " << dist(ld, rd) << "\n";
        ans[i] = len + 1;
    }
    for(int i = 1; i <= n; i++){
        if(i & 1)cout << 1 << "\n";
        else cout << ans[i / 2] << "\n";
    }
    
}

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