Submission #516362

#	Time	Username	Problem	Language	Result	Execution time	Memory
516362		leaked	Lampice (COCI19_lampice)	C++14	42 / 110	5100 ms	35408 KiB

lampice

#include <bits/stdc++.h>
//#include "debug.h"
//    #pragma GCC optimize("-O3")
//    #pragma GCC optimize("no-stack-protector")
//    #pragma GCC optimize("fast-math")
//    #pragma GCC optimize("Ofast")
//    #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
//    #pragma GCC target("avx,avx2,fma")
//    #pragma GCC optimization ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define fi first
#define f first
#define s second
#define se second
#define vec vector
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
#define sz(x) (int)x.size()
#define pw(x) (1ll<<x)
#define p_b push_back
#define m_p make_pair
#define fast_io ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define sq(x) (x)*(x)
using namespace std;
using namespace __gnu_pbds;
typedef pair<long long, long long> PII;
typedef pair<int, int> pii;
typedef long double ld;
typedef long long ll;
typedef pair<long long, long long > pll;
//template <typename T> umax(T &a, T b){return (a<b ? a=b,1 : 0);}
//template <typename T> umin(T &a, T b){return (a>b ? a=b,1 : 0);}
typedef tree<pii,null_type,less<pii>,rb_tree_tag,tree_order_statistics_node_update> o_set;
const int N=5e4+5;
const ll inf=1e9;
const ld eps = 1e-9;
const int ppp=73;
const int M=99999837;
const ll tx[4]={-1,1,0,0};
const ll ty[4]={0,0,-1,1};
const char rev_to[4]={'U','D','L','R'};
auto rnd=bind(uniform_int_distribution<ll>(1,1e9),mt19937(time(0)));
int dp[N],TO[N];
bool used[N];
vec<int>g[N];
int pp[N];
void recalc(int v,int p){
    dp[v]=1;
    for(auto &z :  g[v]){
        if(!used[z] && z!=p){
            recalc(z,v);
            dp[v]+=dp[z];
        }
    }
}
int get_cen(int v,int p,int sz){
    for(auto &z : g[v]){
        if(z^p && !used[z] && dp[z]>=sz/2){
            return get_cen(z,v,sz);
        }
    }
    return v;
}
int sum(int x,int b){
    x+=b;
    if(x>=M)
        x-=M;
    if(x<0)
        x+=M;
    return x;
}
void add(int &x,int b){
    x+=b;
    if(x<0)
        x+=M;
    if(x>=M)
        x-=M;
}
int mult(const int &a,const int &b){
    return 1ll*a*b%M;
}
int ok;
map<int,int> gp[N];
int len,n,m;
vec<int>hd;
string s;
int Hd[N],Hup[N];
void calc_hd(int v,int p,int to,int dst){
    if(dst>(len/2))
        return;
    Hd[v]=sum(mult(s[v]-'a'+1,pp[dst-1]),Hd[p]);
    gp[dst][mult(Hd[v],pp[N-1])]+=to;
//    debug()<<imie(v)imie(mult(Hd[v],pp[N-dst-1]));
//    if(dst<=(len/2)){
       for(auto &z : g[v]){
            if(!used[z] && z^p){
                calc_hd(z,v,to,dst+1);
            }
        }
//    }
}
vec<int>a;
void calc_hupd(int v,int p,int dl){
    a.pb(v);
    Hup[v]=sum(mult(ppp,Hup[p]),s[v]-'a'+1);
    Hd[v]=sum(mult(s[v]-'a'+1,pp[dl-1]),Hd[p]);
//    debug()<<imie(v)imie(Hd[v])imie(Hup[v]);
    if(dl>=(len+1)/2 && dl<len){
        int rem=len-dl;
        int mh=Hd[v];
        if(dl-rem){
            int pr=a[dl-rem-1];
            add(mh,-Hd[pr]);
            if(Hd[pr]==Hup[pr]){
                mh=mult(mh,pp[N-(dl-rem)-1]);
//                debug()<<imie(rem)imie(gp[rem])imie(mh);
                ok|=gp[rem][mh];
            }
        }
        else{
            mh=mult(mh,pp[N-1]);
            ok|=gp[rem][mh];
        }
    }
    else if(dl>=len){
        if(dl!=len){
            add(Hup[v],-mult(pp[len],s[a[dl-len-1]]-'a'+1));
            int u=a[dl-len-1];
            add(Hd[v],-mult(pp[TO[u]-1],s[u]-'a'+1));
        }
        ok|=(mult(Hup[v],pp[N-1])==mult(Hd[v],pp[N-(dl-len)-1]));
    }
    for(auto &z : g[v]){
        if(!used[z] && z^p){
            TO[v]=z;
            calc_hupd(z,v,dl+1);
        }
    }
    a.pop_back();
}
void dfs(int v){
    recalc(v,v);
    v=get_cen(v,v,dp[v]);
    used[v]=1;
    Hd[v]=s[v]-'a'+1;
    Hup[v]=s[v]-'a'+1;
    a.pb(v);
    for(int i = 1; i >=-1; --i){
        if(!i)
            continue;
        for(auto &z : g[v]){
            if(!used[z]){
                TO[v]=z;
                if(i==1){
                    Hd[v]=s[v]-'a'+1;
                    calc_hupd(z,v,2);
                    Hd[v]=0;
                    calc_hd(z,v,i,1);
                }
                else{
                    Hd[v]=0;
                    calc_hd(z,v,i,1);
                    Hd[v]=s[v]-'a'+1;
                    calc_hupd(z,v,2);
                }
//                cout<<endl;
            }
        }
//        reverse(all(g[v]));

    }
    a.pop_back();
     if(ok)
        return ;
    for(auto &z : g[v]){
        if(!used[z])
            dfs(z);
    }
}
signed main()
{
    fast_io;
    pp[0]=1;
    for(int i = 1 ; i < N; ++i)
        pp[i]=mult(pp[i-1],ppp);
    cin>>n;
    cin>>s;
    for(int i = 1 ; i < n; i++){
        int v,u;
        cin>>v>>u;--v;--u;
        g[v].pb(u);
        g[u].pb(v);
    }
    int ans=1;
    for(int i = 0 ; i <= 1 ;i ++){
        int l=1,r=n/2+1;
        while(l!=r){
            int mid=(l+r)>>1;
            len=2*mid+i;
            ok=0;
            fill(used,used+n,false);
            dfs(0);
            if(ok){
                l=mid+1;
            }
            else{
                r=mid;
            }
        }
        l--;
        ans=max(ans,2*l+i);
    }
    cout<<ans;
    return 0;
}
/*
4
abba
1 2
2 3
3 4
*/

• Subtask 1: 17 / 17
• Subtask 2: 25 / 25
• Subtask 3: 0 / 31
• Subtask 4: 0 / 37