Submission #826276

#	Time	Username	Problem	Language	Result	Execution time	Memory
826276		8pete8	Valley (BOI19_valley)	C++14	100 / 100	220 ms	52904 KiB

valley

#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<algorithm>
#include<limits.h>
#include<cmath>
#include<bitset>
using namespace std;
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,int>
#define pb push_back
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
//#define int long long
#define mod 1000000007
#define int long long
const int mxn=1e5,lg=17,inf=1e18;
vector<pii>adj[mxn+10];
vector<int>shop;
vector<pair<pii,int>>edge;
int up[mxn+10][20],h[mxn+10],sdist[mxn+10],dist[mxn+10];
int dp[mxn+10][20];
void solve(int cur,int p){
    for(auto i:adj[cur]){
        if(i.f==p)continue;
        h[i.f]=h[cur]+1;
        up[i.f][0]=cur;
        dist[i.f]=dist[cur]+i.s;
        solve(i.f,cur);
        sdist[cur]=min(sdist[cur],sdist[i.f]+i.s);
    }
    dp[cur][0]=sdist[cur];
}
int caldist(int a,int b){return abs(dist[a]-dist[b]);}
int cal(int node,int k){
    int ans=inf,d=0;
    for(int i=0;i<=lg;i++){
        if(k&(1<<i)){
            ans=min(ans,dp[node][i]+d);
            d+=abs(dist[node]-dist[up[node][i]]);
            node=up[node][i];
        }
    }
    return ans;
}
int32_t main(){
    fastio
    int n,m,q,e;cin>>n>>m>>q>>e;
    for(int i=0;i<n-1;i++){
        int u,v,w;cin>>u>>v>>w;
        adj[u].pb({v,w});
        adj[v].pb({u,w});
        edge.pb({{u,v},w});
    }
    fill(sdist,sdist+n+1,inf);
    for(int i=1;i<=lg;i++)for(int j=1;j<=n;j++)dp[j][i]=inf;
    for(int i=0;i<m;i++){
        int a;cin>>a;
        sdist[a]=0;
    }
    solve(e,-1);
    for(int i=1;i<=lg;i++){
        for(int j=1;j<=n;j++){
            up[j][i]=up[up[j][i-1]][i-1];
            dp[j][i]=min(dp[j][i-1],abs(dist[j]-dist[up[j][i-1]])+dp[up[j][i-1]][i-1]);
        }
    }
    while(q--){
        int a,b;cin>>a>>b;
        a--;
        if(h[edge[a].f.f]>h[edge[a].f.s])a=edge[a].f.f;
        else a=edge[a].f.s;
        if(h[a]<=h[b]){
            int cur=b;
            int k=h[b]-h[a];
            for(int i=0;i<=lg;i++)if(k&(1<<i))cur=up[cur][i];
            if(cur==a){
                int k=h[b]-h[a]+1;
                int g=cal(b,k);
                if(g!=inf)cout<<g<<'\n';
                else cout<<"oo"<<'\n';
            }
            else cout<<"escaped"<<'\n';
        }
        else cout<<"escaped"<<'\n';
    }
}

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