Submission #1021895

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021895		m5588ohammed	Valley (BOI19_valley)	C++14	0 / 100	295 ms	29884 KiB

valley

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
int n,S,E,q,U,V,x,l,mn,flag,y;
vector <array<int,2>> v[100001],edges;
priority_queue <array<int,2>> qu;
int shops[100001],t[100001][20],level[100001];
void dfs(int i,int last,int sum){
    if(i==E){
        flag=1;
        return;
    }
    if(shops[i]==1) mn=min(mn,sum);
    for(auto [j,c]:v[i]){
        if((i==U&&j==V)||(i==V&&j==U)||j==last) continue;
        dfs(j,i,sum+c);
    }
    return;
}
void calc1(){
    while(q--){
        flag=0;
        mn=100000000000000000;
        cin>>l>>x;
        U=edges[l-1][0];
        V=edges[l-1][1];
        dfs(x,0,0);
        if(flag==1) cout<<"escaped"<<endl;
        else if(mn!=100000000000000000) cout<<mn<<endl;
        else cout<<"oo"<<endl;
    }
}
void parent(int i,int last){
    t[i][0]=last;
    level[i]=level[last]+1;
    for(auto [j,c]:v[i]) if(j!=last) parent(j,i);
    return;
}
int lca(int a,int b){
    int la=level[a],lb=level[b],k;
    if(la<lb){
        swap(a,b);
        swap(la,lb);
    }
    k=la-lb;
    for(int i=20;i>=0;i--){
        if(k-(1<<i)>=0){
            k-=(1<<i);
            a=t[a][i];
        }
    }
    if(a==b) return a;
    for(int i=20;i>=0;i--){
        if(t[a][i]!=t[b][i]){
            a=t[a][i];
            b=t[b][i];
        }
    }
    return t[a][0];
}
void calc2(){
    for(int k=1;k<=20;k++) for(int i=1;i<=n;i++) t[i][k]=t[t[i][k-1]][k-1];
    while(q--){
        cin>>l>>x;
        if(level[edges[l-1][0]]>level[edges[l-1][1]]) y=edges[l-1][0];
        else y=edges[l-1][1];
        if(lca(lca(E,x),y)!=lca(E,x)) cout<<"escaped"<<endl;
        else cout<<0<<endl;
    }
}
signed main()
{
    cin>>n>>S>>q>>E;
    for(int i=0;i<n-1;i++){
        int a,b,c;
        cin>>a>>b>>c;
        v[a].push_back({b,c});
        v[b].push_back({a,c});
        edges.push_back({a,b});
    }
    for(int i=0;i<S;i++){
        int a;
        cin>>a;
        shops[a]=1;
    }
    if(S!=n) calc1();
    else calc2();
    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'void dfs(long long int, long long int, long long int)':
valley.cpp:15:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   15 |     for(auto [j,c]:v[i]){
      |              ^
valley.cpp: In function 'void parent(long long int, long long int)':
valley.cpp:37:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   37 |     for(auto [j,c]:v[i]) if(j!=last) parent(j,i);
      |              ^

• Subtask 1: 0 / 9
• Subtask 2: 0 / 27
• Subtask 3: 0 / 23
• Subtask 4: 0 / 41