Submission #535105

#	Time	Username	Problem	Language	Result	Execution time	Memory
535105		__Variatto	Valley (BOI19_valley)	C++17	100 / 100	430 ms	46172 KiB

valley

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define ll long long
const int MAX=1e5+10, L=19;
const ll MAXV=1e16;
int n, s, q, e, a[MAX], b[MAX], w;
bool sk[MAX];
vector<pair<int,int>>g[MAX];
int czas, pre[MAX], maxiPre[MAX];
ll naj[MAX], gle[MAX], gle2[MAX];
pair<int,ll>jump[MAX][L];
pair<int,int> o[MAX];
void dfs(int v, int oj){
    pre[v]=++czas;
    naj[v]=MAXV;
    if(sk[v])
        naj[v]=0;
    for(auto s:g[v]){
        if(s.fi!=oj){
            gle[s.fi]=gle[v]+1;
            gle2[s.fi]=gle2[v]+s.se;
            o[s.fi]={v, s.se};
            dfs(s.fi, v);
            naj[v]=min(naj[v], naj[s.fi]+(ll)s.se);
        }
    }
    maxiPre[v]=czas;
}
int main(){
/*    ios_base::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
*/    cin>>n>>s>>q>>e;
    for(int i=1; i<=n-1; i++){
        cin>>a[i]>>b[i]>>w;
        g[a[i]].pb({b[i], w}), g[b[i]].pb({a[i], w});
    }
    for(int i=1; i<=s; i++){
        int c;
        cin>>c;
        sk[c]=true;
    }
    dfs(e, e);
    for(int i=1; i<=n; i++)
        jump[i][0]={o[i].fi, min(naj[i], o[i].se+naj[o[i].fi])};
    for(int i=1; i<L; i++){
        for(int j=1; j<=n; j++){
            jump[j][i].fi=jump[jump[j][i-1].fi][i-1].fi;
            jump[j][i].se=min(jump[j][i-1].se, jump[jump[j][i-1].fi][i-1].se+gle2[j]-gle2[jump[j][i-1].fi]);
        }
    }
    while(q--){
        int x, y;
        cin>>x>>y;
        int u1=a[x], u2=b[x];
        if(pre[u1]>pre[u2])
            swap(u1, u2);
        if(pre[u2]>pre[y] || maxiPre[u2]<pre[y]){
            cout<<"escaped\n";
            continue;
        }
        if(naj[u2]==MAXV){
            cout<<"oo\n";
            continue;
        }
        int doU2=gle[y]-gle[u2];
        //cout<<doU2<<"\n";
        int y1=y, licz=0;
        ll odl=naj[y], akt=0;
        while(doU2){
            if(doU2%2){
                //cout<<y1<<" "<<licz<<" "<<jump[y1][licz].se<<"\n";
                odl=min(odl, akt+jump[y1][licz].se);
                akt+=gle2[y1]-gle2[jump[y1][licz].fi];
                y1=jump[y1][licz].fi;
            }
            doU2/=2, licz++;
        }
        cout<<odl<<"\n";
    }
}

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