oj.uz

답안 #851420

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
851420 2023-09-19T18:00:14 Z vjudge1 Papričice (COCI20_papricice) C++17
0 / 110
 2 ms 8028 KB 
#pragma GCC optimize("unroll-loops,Ofast,O3")
#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define spc << " " <<
#define all(x) x.begin(), x.end()
#define ll long long
#define int long long
#define ii pair<int,int>
#define vi vector<int>
#define vii vector<ii>
#define st first
#define nd second
#define inf 1000000009
#define MOD 998244353
using namespace std;




vi edges[200005];
int sub[200005], par[200005];
int lim;

void subby(int node){
    sub[node]=1;
    for(auto i:edges[node]){
        if(par[node]==i || i==0) continue;
        par[i]=node;
        subby(i);
        sub[node]+=sub[i];
    }
}

int dfs(int node){
    for(auto i:edges[node]){
        if(i==par[node] || i==0) continue;

        if(sub[i]>=lim) return dfs(i);
    }
    return node;
}



void solve(){
    int n; cin >> n;
    lim = (n-1)/3+1;
    
    for(int i=1; i<n; i++){
        int a,b; cin >> a >> b;
        edges[a].pb(b);
        edges[b].pb(a);
    }

    par[1]=0;
    subby(1);

    int root = dfs(1);
    int arr[3];
    //cerr << root spc sub[root] << endl;

    if(root==1){
        vi yea;
        for(auto i:edges[1]) yea.pb(sub[i]);
        sort(all(yea), greater<int>());
        //cerr << yea[0] spc yea[1] << endl;
        arr[0] = sub[1]-yea[0]-yea[1];
        arr[1] = yea[0];
        arr[2] = yea[1];
    }
    else if(sub[root]>=n/2){
        arr[0] = sub[1]-sub[root];

        lim = (sub[root]-1)/3+1;
        int root2 = dfs(root);
        arr[1] = sub[root]-sub[root2];
        arr[2] = sub[root2];
        
    }
    else{
        //cerr << "ok" << endl;
        arr[0] = sub[root];
        
        for(auto &i:edges[par[root]]){
            if(i==root){
                i=0;
                break;
            }
        }

        subby(1);
        //for(int i=1; i<=n; i++) cerr << i spc sub[i] << endl;
        lim = (sub[1]-1)/3+1;
        root=dfs(1);
        arr[1] = sub[1]-sub[root];
        arr[2] = sub[root];
    }
    sort(arr, arr+3);
    cout << arr[2]-arr[0] << endl;
}



signed main(){
    ios_base::sync_with_stdio(false);cin.tie(0);
    #ifdef Local
    freopen("in","r",stdin);
    freopen("out","w",stdout);
    #endif


    ll t=1;
    //cin >> t;
    while(t--) solve();
}

Subtask #1
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 8028 KB Output is correct
2 Incorrect 2 ms 8028 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 8028 KB Output is correct
2 Incorrect 2 ms 8028 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #3
0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 2 ms 8028 KB Output is correct
2 Incorrect 2 ms 8028 KB Output isn't correct
3 Halted 0 ms 0 KB -