Submission #693431

#	Time	Username	Problem	Language	Result	Execution time	Memory
693431		anhduc2701	Valley (BOI19_valley)	C++17	100 / 100	240 ms	72576 KiB

valley

/*
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
*/
#include<bits/stdc++.h>
#define int long long
using namespace std;
#define all(x) x.begin(), x.end()
#define len(x) ll(x.size())
#define eb emplace_back
#define PI 3.14159265359
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define BIT(x,i) (1&((x)>>(i)))
#define MASK(x) (1LL<<(x))
#define task "tnc"  
typedef long long ll;
const ll INF=1e18;
const int maxn=1e6+5;
const int mod=1e9+7;
const int mo=998244353;
using pi=pair<ll,ll>;
using vi=vector<ll>;
using pii=pair<pair<ll,ll>,ll>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
vector<pair<int,int>>G[maxn];
int high[maxn];
int h[maxn];
int a[maxn];
pair<pair<int,int>,int>edge[maxn];
int midis[maxn];
int n,s,root,q;
int pa[maxn][19];
int mi[maxn][19];
void dfs(int u,int par){
	for(auto v:G[u]){
		if(v.fi==par)continue;
		high[v.fi]=high[u]+1;
		h[v.fi]=h[u]+v.se;
		pa[v.fi][0]=u;
		dfs(v.fi,u);
		midis[u]=min(midis[u],midis[v.fi]+v.se);
	}
	for(auto v:G[u]){
		mi[v.fi][0]=midis[u]-h[u];
	}
}
int LCA(int u,int v){
    if(high[u]>high[v])swap(u,v);
    int d=high[v]-high[u];
    for(int j=18;j>=0;j--){
        if((1<<j)&d){
            v=pa[v][j];
        }
    }
    if(u==v){
        return u;
    }
    for(int j=18;j>=0;j--){
        if(pa[u][j]!=pa[v][j] && pa[u][j]!=0){
            u=pa[u][j];
            v=pa[v][j];
        }
    }
    return pa[u][0];
}
int fin(int u,int k){
    for(int j=18;j>=0;j--){
        if((1<<j)&k){
            u=pa[u][j];
        }
    }
    return u;
}
int fin1(int u,int k){
	int d=midis[u]-h[u];
    for(int j=18;j>=0;j--){
        if((1<<j)&k){
        	d=min(d,mi[u][j]);
            u=pa[u][j];
        }
    }
    return d;	
}
void init(){
    for(int j=1;(1<<j)<=n;j++){
        for(int i=1;i<=n;i++){
            pa[i][j]=pa[pa[i][j-1]][j-1];
            mi[i][j]=min(mi[i][j-1],mi[pa[i][j-1]][j-1]);
        }
    }
}
int getdist(int u,int v){
    return high[u]+high[v]-2*high[LCA(u,v)];
}
signed main()
{
	cin.tie(0),cout.tie(0)->sync_with_stdio(0);
    
    cin>>n>>s>>q>>root;
    for(int i=1;i<n;i++){
    	int u,v,w;
    	cin>>u>>v>>w;
    	edge[i]={{u,v},w};
    	G[u].pb({v,w});
    	G[v].pb({u,w});
    }
    for(int i=1;i<=n;i++){
    	midis[i]=INF;
    }
    for(int i=1;i<=s;i++){
    	cin>>a[i];
    	midis[a[i]]=0;
    }
    dfs(root,root);
    init();
    for(int i=1;i<=q;i++){
    	int index,r;
    	cin>>index>>r;
    	int u=edge[index].fi.fi;
    	int v=edge[index].fi.se;
    	if(pa[v][0]==u)swap(v,u);
    	if(LCA(r,u)!=u){
    		cout<<"escaped\n";
    	}
    	else{
    		int k=high[r]-high[u];
    		int d1=fin1(r,k);
    		if(d1+h[r]>=1e14){
    			cout<<"oo\n";
    		}
    		else{
    			cout<<d1+h[r]<<"\n";
    		}
    	}
    }
    return 0;
}

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