Submission #1087104

#	Time	Username	Problem	Language	Result	Execution time	Memory
1087104		PieArmy	Valley (BOI19_valley)	C++17	100 / 100	170 ms	52308 KiB

valley

typedef long long ll;
ll pie(ll army){return (1ll<<army);}
#include <bits/stdc++.h>
#define fr first
#define sc second
#define pb push_back
#define endl '\n'
#define mid ((left+right)>>1)
const ll inf=2000000000000000005;
const int sonsuz=2000000005;
using namespace std;
ll fpow(ll x,ll y,ll m=0){if(y<0){cout<<"powError";return -1;}if(m)x%=m;ll res=1;while(y>0){if(y&1)res*=x;x*=x;if(m){x%=m;res%=m;}y>>=1;}return res;}

int n,s,q,root;
int dep[100001],par[100001][17];
ll dis[100001][17],res[100001][17];
ll bes[100001];
int shop[100001];
vector<pair<int,pair<int,int>>>komsu[100001];
int subroot[100001];

void dfs(int pos){
	for(int i=1;i<17;i++){
		par[pos][i]=par[par[pos][i-1]][i-1];
		dis[pos][i]=dis[pos][i-1]+dis[par[pos][i-1]][i-1];
	}
	if(shop[pos])bes[pos]=0;
	for(pair<int,pair<int,int>>x:komsu[pos]){
		if(x.fr==par[pos][0]){
			subroot[x.sc.sc]=pos;
			continue;
		}
		par[x.fr][0]=pos;
		dis[x.fr][0]=x.sc.fr;
		dep[x.fr]=dep[pos]+1;
		dfs(x.fr);
		bes[pos]=min(bes[pos],bes[x.fr]+x.sc.fr);
	}
}

void code(){
	cin>>n>>s>>q>>root;
	for(int i=1;i<=n;i++){
		bes[i]=inf;
	}
	for(int i=1;i<n;i++){
		int x,y,w;
		cin>>x>>y>>w;
		komsu[x].pb({y,{w,i}});
		komsu[y].pb({x,{w,i}});
	}
	par[root][0]=root;
	for(int i=1;i<=s;i++){
		int x;cin>>x;
		shop[x]=1;
	}
	dfs(root);
	for(int i=1;i<=n;i++){
		res[i][0]=min(bes[i],bes[par[i][0]]+dis[i][0]);
	}
	for(int i=1;i<17;i++){
		for(int j=1;j<=n;j++){
			res[j][i]=min(res[j][i-1],res[par[j][i-1]][i-1]+dis[j][i-1]);
		}
	}
	while(q--){
		int a,b;cin>>b>>a;
		b=subroot[b];
		ll ans=bes[a];
		if(dep[b]>dep[a]){
			cout<<"escaped\n";
			continue;
		}
		ll sum=0;
		for(int i=0;i<17;i++){
			if((dep[a]-dep[b])&pie(i)){
				ans=min(ans,res[a][i]+sum);
				sum+=dis[a][i];
				a=par[a][i];
			}
		}
		if(a!=b){
			cout<<"escaped\n";
			continue;
		}
		if(ans==inf){
			cout<<"oo\n";
			continue;
		}
		cout<<ans<<endl;
	}
}

int main(){
	ios_base::sync_with_stdio(false);cin.tie(NULL);
	bool usaco=0;if(usaco){freopen(".in","r",stdin);freopen(".out","w",stdout);}
	int t=1;
	if(!t)cin>>t;
	while(t--){code();cout<<endl;}
	return 0;
}

Compilation message (stderr)

valley.cpp: In function 'int main()':
valley.cpp:96:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |  bool usaco=0;if(usaco){freopen(".in","r",stdin);freopen(".out","w",stdout);}
      |                         ~~~~~~~^~~~~~~~~~~~~~~~~
valley.cpp:96:57: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |  bool usaco=0;if(usaco){freopen(".in","r",stdin);freopen(".out","w",stdout);}
      |                                                  ~~~~~~~^~~~~~~~~~~~~~~~~~~

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