제출 #1281950

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1281950		quan606303	Lampice (COCI19_lampice)	C++20	0 / 110	84 ms	12888 KiB

lampice

/*
 * @Author: RMQuan 
 * @Date: 2025-10-22 13:30:19 
 * @Last Modified by: RMQuan
 * @Last Modified time: 2025-10-22 15:50:00
 */
#include <bits/stdc++.h>
bool M1;
#define int long long
#define ll long long
#define INTMAX INT_MAX
#define INTMIN INT_MIN
#define LONGMAX LLONG_MAX
#define LONGMIN LLONG_MIN
#define fi first
#define se second
#define memfull(a,b) memset(a,b,sizeof(a));
#define endl '\n'
#define TASK "TEST"
#define file() if (fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin); freopen(TASK".out","w",stdout);}
using namespace std;

const int MOD=1000000007;
const int maxn=50005;

int n,base=911382323;
string S;
vector<int> adj[maxn];
bool is_deleted[maxn];
int sz[maxn],pw[maxn];

int addm(int x,int y){ x%=MOD; y%=MOD; x+=y; if(x>=MOD) x-=MOD; return x; }
int subm(int x,int y){ x%=MOD; y%=MOD; x-=y; if(x<0) x+=MOD; return x; }
int mulm(int x,int y){ return (int)((1LL*(x%MOD)*(y%MOD))%MOD); }

void pre_dfs(int u,int p){
    sz[u]=1;
    for (int i=0;i<(int)adj[u].size();i++){
        int v=adj[u][i];
        if (v==p||is_deleted[v]) continue;
        pre_dfs(v,u);
        sz[u]+=sz[v];
    }
}
int find_centroid(int u,int p,int tot){
    for (int i=0;i<(int)adj[u].size();i++){
        int v=adj[u][i];
        if (v==p||is_deleted[v]) continue;
        if (sz[v]>tot/2) return find_centroid(v,u,tot);
    }
    return u;
}

void DFS(int u,int p,int depth,int half,int &Hf,int &Hb,vector<pair<int,int> > &col){
    if (depth>half) return;
    int val=S[u]-'a'+1;
    Hf = addm(mulm(Hf,base), val);
    Hb = addm(Hb, mulm(val, pw[depth-1]));
    col.push_back({Hf,Hb});
    if (depth==half) return;
    for (int i=0;i<(int)adj[u].size();i++){
        int v=adj[u][i];
        if (v==p||is_deleted[v]) continue;
        int nHf=Hf, nHb=Hb;
        DFS(v,u,depth+1,half,nHf,nHb,col);
    }
}

bool check_even_at_root(int root,int L){
    if (L&1) return false;
    int half=L/2;
    if (half==0) return true;
    static vector<vector<pair<int,int> > > all; all.clear();
    for (int i=0;i<(int)adj[root].size();i++){
        int v=adj[root][i];
        if (is_deleted[v]) continue;
        vector<pair<int,int> > col;
        int Hf=0,Hb=0;
        DFS(v,root,1,half,Hf,Hb,col);
        if (!col.empty()) all.push_back(col);
    }
    vector<unordered_set<long long> > seen(half+1);
    for (int i=0;i<(int)all.size();i++){
        for (int t=0;t<(int)all[i].size();t++){
            int d=t+1;
            int Hf=all[i][t].fi;
            if (seen[d].count((long long)Hf)) return true;
        }
        for (int t=0;t<(int)all[i].size();t++){
            int d=t+1;
            int Hb=all[i][t].se;
            seen[d].insert((long long)Hb);
        }
    }
    return false;
}

bool check_odd_at_root(int root,int L){
    if ((L&1)==0) return false;
    int half=(L-1)/2;
    if (half==0) return true;
    static vector<vector<pair<int,int> > > all; all.clear();
    for (int i=0;i<(int)adj[root].size();i++){
        int v=adj[root][i];
        if (is_deleted[v]) continue;
        vector<pair<int,int> > col;
        int Hf=0,Hb=0;
        DFS(v,root,1,half,Hf,Hb,col);
        if (!col.empty()) all.push_back(col);
    }
    vector<unordered_set<long long> > seen(half+1);
    for (int i=0;i<(int)all.size();i++){
        for (int t=0;t<(int)all[i].size();t++){
            int d=t+1;
            int Hf=all[i][t].fi;
            if (seen[d].count((long long)Hf)) return true;
        }
        for (int t=0;t<(int)all[i].size();t++){
            int d=t+1;
            int Hb=all[i][t].se;
            seen[d].insert((long long)Hb);
        }
    }
    return false;
}

bool check_at_root(int root,int L){
    if (check_even_at_root(root,L)) return true;
    if (check_odd_at_root(root,L)) return true;
    return false;
}

bool solve_centroid(int entry,int L){
    pre_dfs(entry,0);
    int tot=sz[entry];
    int c=find_centroid(entry,0,tot);
    is_deleted[c]=true;
    if (check_at_root(c,L)) return true;
    for (int i=0;i<(int)adj[c].size();i++){
        int v=adj[c][i];
        if (!is_deleted[v]){
            if (solve_centroid(v,L)) return true;
        }
    }
    return false;
}

bool checkL(int L){
    for (int i=1;i<=n;i++) is_deleted[i]=false;
    return solve_centroid(1,L);
}

int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    file();
    cin>>n>>S; S="$"+S;
    for (int i=1;i<n;i++){
        int x,y; cin>>x>>y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    pw[0]=1; for (int i=1;i<=n;i++) pw[i]=mulm(pw[i-1],base);

    int lo=1,hi=n,ans=1;
    while (lo<=hi){
        int mid=(lo+hi)>>1;
        if (checkL(mid)) ans=mid, lo=mid+1;
        else hi=mid-1;
    }
    cout<<ans<<endl;

    bool M2;
    cerr<<"-------------------------------------------------"<<endl;
    cerr<<"Time : "<<clock()<<" ms"<<endl;
    cerr<<"Memory : "<<llabs(&M2-&M1)/1024/1024<<" MB"<<endl;
    cerr<<"-------------------------------------------------"<<endl;
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

lampice.cpp: In function 'int32_t main()':
lampice.cpp:20:50: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 | #define file() if (fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin); freopen(TASK".out","w",stdout);}
      |                                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:157:5: note: in expansion of macro 'file'
  157 |     file();
      |     ^~~~
lampice.cpp:20:81: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 | #define file() if (fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin); freopen(TASK".out","w",stdout);}
      |                                                                          ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
lampice.cpp:157:5: note: in expansion of macro 'file'
  157 |     file();
      |     ^~~~

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