Submission #642056

#	Time	Username	Problem	Language	Result	Execution time	Memory
642056		Urvuk3	Valley (BOI19_valley)	C++17	100 / 100	285 ms	35476 KiB

valley

#include <bits/stdc++.h>

using namespace std;

#define ll long long
const int INF=1e9;
const ll LINF=1e18;
#define fi first
#define se second
#define pii pair<int,int>
#define pll pair<long long,long long>
#define mid ((l+r)/2)
#define sz(a) (int((a).size()))
#define all(a) a.begin(),a.end()
#define endl "\n"
#define PRINT(x) cerr<<#x<<'='<<x<<endl;
#define pb push_back
#define PRINTvec(niz) { cerr<<#niz<<"="; for(auto _i:niz) cerr<<_i<<" "; cerr<<endl; }

void Solve(){
    int N,S,Q,E; cin>>N>>S>>Q>>E;
    vector<pll> adj[N+1];
    vector<pii> edges(N);
    for(int i=1;i<=N-1;i++){
        int u,v,w; cin>>u>>v>>w;
        adj[u].pb({v,w});
        adj[v].pb({u,w});
        edges[i]={u,v};
    }
    vector<bool> spec(N+1,false);
    for(int i=1;i<=S;i++){
        int x; cin>>x; spec[x]=true;
    }
    struct Kveri{
        int idx,I;
    };
    vector<ll> res(Q+1);
    vector<Kveri> qu[N+1];
    for(int i=1;i<=Q;i++){
        int I,R; cin>>I>>R;
        qu[R].pb({i,I});
    }
    vector<ll> dub_root(N+1),dp(N+1),seg(4*(N+1),LINF);
    vector<int> dub(N+1);
    function<void(int,int,ll)> Dfs1=[&](int node,int prev,ll w){
        dub_root[node]=(node!=E ? dub_root[prev]+w : 0);
        dub[node]=(node!=E ? dub[prev]+1 : 1);
        dp[node]=(spec[node] ? 0 : LINF);
        for(pll p:adj[node]){
            if(p.fi!=prev) Dfs1(p.fi,node,p.se);
            if(p.fi!=prev) dp[node]=min(dp[node],dp[p.fi]+p.se);
        }
    }; Dfs1(E,0,0);
    function<void(int,int,int,int,ll)> Update=[&](int node,int l,int r,int idx,ll val){
        if(l==r){
            seg[node]=val;
            return;
        }
        if(idx<=mid) Update(2*node,l,mid,idx,val);
        else Update(2*node+1,mid+1,r,idx,val);
        seg[node]=min(seg[2*node],seg[2*node+1]);
    };
    function<ll(int,int,int,int,int)> Query=[&](int node,int l,int r,int L,int R){
        if(L>R) return LINF;
        if(L<=l && r<=R) return seg[node];
        ll ret=LINF;
        if(L<=mid) ret=min(ret,Query(2*node,l,mid,L,R));
        if(R>mid) ret=min(ret,Query(2*node+1,mid+1,r,L,R));
        return ret;
    };
    set<int> parents;
    function<void(int,int)> Dfs2=[&](int node,int prev){
        parents.insert(node);
        for(Kveri q:qu[node]){
            int u=edges[q.I].fi,v=edges[q.I].se;
            int idx=q.idx;
            if(dub[u]<dub[v]) swap(u,v);
            if(!parents.count(u)) res[idx]=-2;
            else{
                int L=dub[u],R=dub[node];
                res[idx]=min(Query(1,1,N,L,R)+dub_root[node],dp[node]);
                res[idx]=(res[idx]<LINF ? res[idx] : -1);
            }
        }
        Update(1,1,N,dub[node],dp[node]-dub_root[node]);
        for(pll p:adj[node]){
            if(p.fi!=prev) Dfs2(p.fi,node);
        }
        Update(1,1,N,dub[node],LINF);
        parents.erase(parents.find(node));
    }; Dfs2(E,0);
    for(int i=1;i<=Q;i++){
        if(res[i]==-2) cout<<"escaped"<<endl;
        else if(res[i]==-1) cout<<"oo"<<endl;
        else cout<<res[i]<<endl;
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t;
    //cin>>t;
    t=1;
    while(t--){
        Solve();
    }
    return 0;
}

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