Submission #155146

#	Time	Username	Problem	Language	Result	Execution time	Memory
155146		GoldNextYear	Valley (BOI19_valley)	C++14	100 / 100	854 ms	53540 KiB

valley

#define fast ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#include <bits/stdc++.h>
using namespace std;
#define sqr 340
#define mid (l+r)/2
#define pb push_back
#define pob pop_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define ins insert
#define era erase
#define C continue
#define mem(dp,i) memset(dp,i,sizeof(dp))
#define mset multiset
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pi;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pi> vpi;
typedef vector<pll> vpll;
const ll mod=1000000007;
const ll inf=1e18*4;
const ld pai=acos(-1);
ll n,s,q,root;
ll timer;
vpll v[100009];
pll e[100009];
ll shop[100009];
ll jumpnode[100009][20],jumpmagic[100009][20],magic[100009];
ll depth[100009],st[100009],en[100009],w[100009];
void dfs_calc(int node,int p,ll t){
        depth[node]=t;
        w[node]=w[p]+1;
        st[node]=timer++;
        for(auto u:v[node]){
                if(u.fi!=p)dfs_calc(u.fi,node,t+u.se);
        }
        en[node]=timer-1;
}
void dfs_magic(int node,int p){
        if(shop[node])magic[node]=depth[node];
        else magic[node]=inf;
        for(auto u:v[node]){
                if(u.fi!=p){
                        dfs_magic(u.fi,node);
                        magic[node]=min(magic[node],magic[u.fi]);
                }
        }
}
void fill_magic(){
        for(int i=0;i<n;i++)magic[i]-=2*depth[i];
}
void dfs_lca(int node,int p){
        jumpnode[node][0]=p;
        jumpmagic[node][0]=min(magic[node],magic[p]);
        for(auto u:v[node]){
                if(u.fi!=p)dfs_lca(u.fi,node);
        }
}
void fill_lca(){
        for(int j=1;j<20;j++){
                for(int i=0;i<n;i++){
                        jumpnode[i][j]=jumpnode[jumpnode[i][j-1]][j-1];
                        jumpmagic[i][j]=min(jumpmagic[jumpnode[i][j-1]][j-1],jumpmagic[i][j-1]);
                }
        }
}
int check(int a,int b,int x){
        if(w[a]<w[b])swap(a,b);
        return (st[a]<=st[x] && en[a]>=st[x]);
}
ll solve(int u,int p){
        int l=w[u]-w[p];
        ll mn=inf;
        for(int i=0;i<20;i++){
                if((l&(1<<i))){
                        mn=min(mn,jumpmagic[u][i]);
                        u=jumpnode[u][i];
                }
        }
        return min(mn,magic[p]);
}
int main(){
        cin>>n>>s>>q>>root;
        root--;
        for(int i=0;i<n;i++){
                for(int j=0;j<20;j++)jumpnode[i][j]=root,jumpmagic[i][j]=inf;
        }
        for(int i=0;i<n-1;i++){
                ll a,b,c;cin>>a>>b>>c,a--,b--;
                e[i]={a,b};
                v[a].pb({b,c});
                v[b].pb({a,c});
        }
        for(int i=0;i<s;i++){
                int x;cin>>x,x--;
                shop[x]=1;
        }
        dfs_calc(root,root,0);
        dfs_magic(root,root),fill_magic();
        dfs_lca(root,root);fill_lca();
        while(q--){
                int id,node;
                cin>>id>>node,id--,node--;
                int a=e[id].fi,b=e[id].se;
                if(!check(a,b,node))cout<<"escaped"<<endl;
                else{
                        int xxx=-1;
                        if(w[a]>w[b])xxx=a;
                        else xxx=b;
                        ll ans=depth[node]+solve(node,xxx);
                        if(ans>1e17)cout<<"oo"<<endl;
                        else cout<<ans<<endl;
                }
        }
}

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 41 / 41