Submission #880166

#	Time	Username	Problem	Language	Result	Execution time	Memory
880166		Ahmed_Solyman	Papričice (COCI20_papricice)	C++14	0 / 110	2 ms	5724 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 n,subtree[N];
int dfs(int node,int parent){
    subtree[node]=1;
    for(auto i:adj[node]){
        if(i!=parent){
            subtree[node]+=dfs(i,node);
        }
    }
    return subtree[node];
}
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;
}
set<int>s;
void solve2(int node,int p){ // others
    if(s.size()){
        int x=n-subtree[node];
        auto iter=s.lower_bound(x>>1);
        if(iter!=s.end()){
            int ch=*iter;
            //ans=min(ans,max({n-subtree[node]-subtree[x],subtree[x],subtree[node]})-min({n-subtree[node]-subtree[x],subtree[x],subtree[node]}));
        }
        if(iter!=s.begin()){
            int ch=*(--iter);
            //ans=min(ans,max({n-subtree[node]-subtree[x],subtree[x],subtree[node]})-min({n-subtree[node]-subtree[x],subtree[x],subtree[node]}));
        }
    }
    for(auto i:adj[node]){
        if(i!=p){
            solve2(i,node);
        }
    }
    s.insert(subtree[node]);
}
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);
    solve2(1,1);
    cout<<ans<<endl;
    return 0;
}

Compilation message (stderr)

papricice.cpp: In function 'void solve2(int, int)':
papricice.cpp:79:17: warning: unused variable 'ch' [-Wunused-variable]
   79 |             int ch=*iter;
      |                 ^~
papricice.cpp:83:17: warning: unused variable 'ch' [-Wunused-variable]
   83 |             int ch=*(--iter);
      |                 ^~

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