Submission #411534

#	Time	Username	Problem	Language	Result	Execution time	Memory
411534		ak2006	Valley (BOI19_valley)	C++14	0 / 100	8 ms	6988 KiB

valley

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vi = vector<int>;
using vvi = vector<vi>;
using vb = vector<bool>;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define pb push_back
void setIO()
{
	fast;
	#ifndef ONLINE_JUDGE
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
	#endif
}
int n = 1e5 + 5,s,q,root;
vi in(n),out(n);
vvvl adj(n);
vb shop(n);
int t;
void dfs(int u,int p)
{
	in[u] = t++;
	for (auto x:adj[u]){
		int v = x[0];
		if (v == p)continue;
		dfs(v,u);
	}
	out[u] = t++;
}
bool is_ancestor(int u,int v)
{
	return in[u] <= in[v] && out[u] >= out[v];
}
int main()
{
	setIO();	
	cin>>n>>s>>q>>root;
	vvi edges;
	for (int i = 1;i<n;i++){
		int u,v,w;
		cin>>u>>v>>w;
		adj[u].pb({v,w});
		adj[v].pb({u,w});
		edges.pb({u,v});
	}
	dfs(root,-1);
	for (int i = 1;i<=s;i++){
		int x;
		cin>>x;
		shop[x] = 1;
	}
	while (q--){
		int pos,u;
		cin>>pos>>u;
		int child = edges[pos - 1][0],par = edges[pos - 1][1];
		if (in[child] < in[par])swap(child,par);
		if (!is_ancestor(child,u))cout<<"escaped"<<'\n';
		else cout<<0<<'\n';
	}
	return 0;
}

Compilation message (stderr)

valley.cpp: In function 'void setIO()':
valley.cpp:16:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |  freopen("input.txt","r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:17:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |  freopen("output.txt","w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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