#include <bits/stdc++.h> #define tt cin.tie(0), cout.tie(0), ios_base::sync_with_stdio(0) #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout) #define ll long long #define ull unsigned long long #define i128 __int128 #define db long double #define sz(a) ((int)(a).size()) #define pb emplace_back #define pf emplace_front #define pob pop_back #define pof pop_front #define lb lower_bound #define ub upper_bound #define fi first #define se second #define ins emplace #define mp make_pair using namespace std; const int MOD = 1e9+7, MAXN = 1e5+5; const string NAME = ""; int n,m,q,root,depth[MAXN],par[MAXN][20],in[MAXN],out[MAXN],id=0; ll dist[MAXN],mindist[MAXN],val[MAXN][20]; bool shop[MAXN]; pair<int,int> edge[MAXN]; vector<pair<int,int>> adj[MAXN]; void dfs(int u){ if(shop[u]) mindist[u]=0; in[u]=++id; for(pair<int,int>& e : adj[u]){ if(e.fi==par[u][0]) continue; depth[e.fi]=depth[u]+1, dist[e.fi]=dist[u]+e.se, par[e.fi][0]=u; for(int i = 1; i<=__lg(n); ++i) par[e.fi][i]=par[par[e.fi][i-1]][i-1]; dfs(e.fi); mindist[u]=min(mindist[u],mindist[e.fi]+e.se); } val[u][0]=dist[u]-mindist[u]; out[u]=id; } int main() { tt; if(fopen((NAME + ".INP").c_str(), "r")) fo; cin >> n >> m >> q >> root; for(int i = 1; i<n; ++i){ int x,y,z; cin >> x >> y >> z; adj[x].pb(y,z), adj[y].pb(x,z); edge[i]={x,y}; } for(int i = 1; i<=m; ++i){ int x; cin >> x; shop[x]=1; } memset(mindist,0x3f,sizeof(mindist)); dfs(root); for(int i = 1; i<=__lg(n); ++i) for(int j = 1; j<=n; ++j) val[j][i]=max(val[j][i-1],val[par[j][i-1]][i-1]); while(q--){ int x,u; cin >> x >> u; x=(depth[edge[x].fi]>depth[edge[x].se] ? edge[x].fi : edge[x].se); if(in[x]<=in[u]&&in[u]<=out[x]){ if(mindist[x]>=1e18) cout << "oo\n"; else{ ll rs=1e18; for(int i = __lg(n); i>=0; --i) if(depth[u]-(1<<i)+1>=depth[x]) rs=min(rs,dist[u]-val[u][i]), u=par[u][i]; cout << rs << "\n"; } }else cout << "escaped\n"; } }

valley.cpp: In function 'int main()':
valley.cpp:3:19: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |            ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:44:45: note: in expansion of macro 'fo'
   44 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~
valley.cpp:3:63: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |                                                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:44:45: note: in expansion of macro 'fo'
   44 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~