Submission #358344

#	Time	Username	Problem	Language	Result	Execution time	Memory
358344		egekabas	Papričice (COCI20_papricice)	C++14	15 / 110	8 ms	5228 KiB

papricice

#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<ll, ll> pii;
typedef pair<ld, ld> pld;
ll n;
ll calcval(ll a, ll b){
    ll c = n-a-b;
    return max({abs(a-b), abs(a-c), abs(b-c)});
}
ll ans = 1e18;
    
vector<ll> g[200009];
multiset<ll> s, ins;
ll sz[200009];
void dfs1(ll v, ll prt){
    sz[v] = 1;
    for(auto u : g[v])
        if(u != prt){
            dfs1(u, v);
            sz[v] += sz[u];
        }
    s.insert(sz[v]);
}
void calc(ll x, ll opt, multiset<ll> &s, ll type){
    auto it = s.lower_bound(opt);
    if(it != s.end()){
        if(type)
            ans = min(ans, calcval(x-*it, *it));
        else    
            ans = min(ans, calcval(x, *it));
    }
    if(it != s.begin()){
        --it;
        if(type)
            ans = min(ans, calcval(x-*it, *it));
        else    
            ans = min(ans, calcval(x, *it));
    }
}
void clean(ll v, ll prt, ll type){
    if(type == 1){
        s.insert(sz[v]);
        ins.erase(ins.lower_bound(sz[v]));
    }
    else{
        s.erase(s.lower_bound(sz[v]));
        ins.insert(sz[v]);
    }
    for(auto u : g[v])
        if(u != prt)
            clean(u, v, type);
}
void dfs2(ll v, ll prt, ll del){
    pii maxi = {0, 0};
    for(auto u : g[v])
        if(u != prt)
            maxi = max(maxi, {sz[u], u});
    for(auto u : g[v])
        if(u != prt && u != maxi.ss)
            dfs2(u, v, 0);
    if(maxi.ss)
        dfs2(maxi.ss, v, 1);

    s.erase(s.lower_bound(sz[v]));
    calc(sz[v], (n-sz[v])/2, s, 0);
    calc(sz[v], sz[v]/2, ins, 1);
    ins.insert(sz[v]);

    
    if(del == 1){
        for(auto u : g[v])
            if(u != prt && u != maxi.ss)
                clean(u, v, 0);
    }
    else{
        s.insert(sz[v]);
        ins.erase(ins.lower_bound(sz[v]));
        if(maxi.ss)
            clean(maxi.ss, v, 1);
    }
}
    
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    
    cin >> n;
    for(ll i = 0; i < n-1; ++i){
        ll x, y;
        cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
    }
    
    dfs1(1, 0);
    dfs2(1, 0, 0);
    cout << ans << '\n';
}

• Subtask 1: 15 / 15
• Subtask 2: 0 / 35
• Subtask 3: 0 / 60