Submission #1064489

#	Time	Username	Problem	Language	Result	Execution time	Memory
1064489		Malix	Valley (BOI19_valley)	C++14	100 / 100	341 ms	46792 KiB

valley

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> tii;
typedef vector<ll> li;
typedef vector<li> lii;
 
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define LSOne(s) ((s)&(-s))
 
ll INF=1000000000000000010;
int inf=2e9+10;
ll M=1e9+7;

int n,m,q,e;
vector<vector<pair<int,ll>>> a;
pii rds;
vi sp,sa,se;
vii p;
vector<ll> tmp;
vector<vector<ll>> dist;
int sval=0,eval=0;

void dfs(int x){
    sa[x]=sval++;
    for(auto u:a[x]){
        if(sa[u.F]!=-1)continue;
        p[u.F][0]=x;
        tmp[u.F]=tmp[x]+u.S;
        dfs(u.F);
        if(dist[u.F][0]!=INF)dist[x][0]=min(dist[x][0],dist[u.F][0]+u.S);
        if(dist[u.F][0]!=INF)dist[u.F][0]-=tmp[u.F];
    }
    se[x]=eval++;
}

bool ances(int x,int y){
    if(sa[x]>=sa[y]&&se[x]<=se[y])return 1;
    return 0;
}

int main() {   
    cin>>n>>m>>q>>e;e--;
    int k=log2(n)+1;
    a.resize(n);p.resize(n,vi(k,-1));sa.resize(n,-1);se.resize(n,-1);dist.resize(n,vector<ll>(k,INF));tmp.resize(n,0);
    REP(i,0,n-1){
        int x,y;ll z;
        cin>>x>>y>>z;
        x--;y--;
        rds.PB({x,y});
        a[x].PB({y,z});
        a[y].PB({x,z});
    }
    sp.resize(m);
    REP(i,0,m)cin>>sp[i];
    REP(i,0,m)sp[i]--;
    REP(i,0,m)dist[sp[i]][0]=0;
    dfs(e);
    REP(j,1,k)REP(i,0,n)if(p[i][j-1]!=-1)p[i][j]=p[p[i][j-1]][j-1];
    REP(j,1,k)REP(i,0,n)if(p[i][j-1]!=-1)dist[i][j]=min(dist[i][j-1],dist[p[i][j-1]][j-1]);
    REP(i,0,n-1)if(sa[rds[i].F]<sa[rds[i].S])swap(rds[i].F,rds[i].S);
    while(q--){
        int x,y;cin>>x>>y;
        x--;y--;
        int z=y;
        if(ances(y,rds[x].F)){
            ll ans=dist[y][0];
            for(int i=k-1;i>=0;i--)if(p[y][i]!=-1&&ances(p[y][i],rds[x].F)){
                ans=min(ans,dist[y][i]);
                y=p[y][i];
            }
            ans=min(ans,dist[y][0]);
            if(ans==INF)cout<<"oo\n";
            else cout<<ans+tmp[z]<<"\n";
        }
        else cout<<"escaped\n";
    }
}

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