Submission #880157

#	Time	Username	Problem	Language	Result	Execution time	Memory
880157		Ahmed_Solyman	Papričice (COCI20_papricice)	C++14	50 / 110	1059 ms	27224 KiB

papricice

/*
In the name of Allah
made by: Ahmed_Solyman
*/
#include <bits/stdc++.h>
#include <ext/rope>
 
using namespace std;
using namespace __gnu_cxx;
#pragma GCC optimize("-Ofast")
#pragma GCC optimize("-O1")
//-------------------------------------------------------------//
typedef long long ll;
typedef unsigned long long ull;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define PI acos(-1)
#define lb lower_bound
#define ub upper_bound
#define endl '\n'
#define all(v) v.begin(),v.end()
#define allr(v) v.rbegin(),v.rend()
#define sum_to(n) (n*(n+1))/2
#define pb push_back
#define pf push_front
#define fil(arr,x) memset(arr,x,sizeof(arr))
const ll mod=1e9+7;
int dx[8]={0,1,0,-1,1,1,-1,-1};
int dy[8]={1,0,-1,0,1,-1,-1,1};
//-------------------------------------------------------------//
ll lcm(ll a,ll b)
{
    return (max(a,b)/__gcd(a,b))*min(a,b);
}
void person_bool(bool x)
{
    cout<<(x?"YES":"NO")<<endl;
}
const int N=2e5+5;
vector<int>adj[N];
int P[N][18],depth[N],n,subtree[N];
int dfs(int node,int parent){
    P[node][0]=parent;
    subtree[node]=1;
    depth[node]=depth[parent]+1;
    for(int k=1;k<18;k++){
        P[node][k]=P[P[node][k-1]][k-1];
    }
    for(auto i:adj[node]){
        if(i!=parent){
            subtree[node]+=dfs(i,node);
        }
    }
    return subtree[node];
}
int lca(int a,int b){
    if(depth[a]<depth[b])swap(a,b);
    for(int k=17;k>=0;k--){
        if(depth[a]-(1<<k)>=depth[b]){
            a=P[a][k];
        }
    }
    if(a==b){
        return a;
    }
    for(int k=17;k>=0;k--){
        if(P[a][k]!=P[b][k]){
            a=P[a][k];
            b=P[b][k];
        }
    }
    return P[a][0];
}
int ans=N;
set<int> solve1(int node,int p){ /// for those whose lca is one of the,
    set<int>s;
    for(auto i:adj[node]){
        if(i!=p){
            set<int>u=solve1(i,node);
            if(u.size()>s.size())swap(u,s);
            for(auto p:u)s.insert(p);
        }
    }
    // n-subtree[node] , subtree[node]-subtree[ch] , subtree[ch]
    auto iter=s.lower_bound(subtree[node]>>1);
    if(iter!=s.end()){
        int ch=*iter;
        ans=min(ans,max({n-subtree[node],subtree[node]-ch,ch})-min({n-subtree[node],subtree[node]-ch,ch}));
    }
    if(iter!=s.begin()){
        int ch=*(--iter);
        ans=min(ans,max({n-subtree[node],subtree[node]-ch,ch})-min({n-subtree[node],subtree[node]-ch,ch}));
    }
    s.insert(subtree[node]);
    return s;
}
int main()
{
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    #ifndef ONLINE_JUDGE
   // freopen("input.in", "r", stdin);
   // freopen("output.out", "w", stdout);
    #endif
    fast
    cin>>n;
    for(int i=0;i<n-1;i++){
        int u,v;cin>>u>>v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    dfs(1,1);
    solve1(1,1);
    for(int i=2;i<=n;i++){
        for(int j=2;j<=n;j++){
            if(i==j){
                continue;
            }
            int k=lca(i,j);
            if(k==i || k==j){
                continue;
            }
            else{
                ans=min(ans,max({n-(subtree[i]+subtree[j]),subtree[i],subtree[j]})-min({n-(subtree[i]+subtree[j]),subtree[i],subtree[j]}));
            }
        }
    }
    cout<<ans<<endl;
    return 0;
}

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