#include <fstream>
#include <vector>
using namespace std;
ifstream cin("file.in");
ofstream cout("file.out");
int n, s, q, e ;
vector<pair<int,int>> edge [1000005];
long long tin[1000005], tout [1000005], shop [1000005], ext[1000005];
long long rev[ 1000005];
vector<int> v;
long long depth [ 300005];
void dfs ( int nod,int p )
{
depth[nod] = depth[p] + 1;
v.push_back(nod);
if (tin[nod] == 0 )
{
tin [nod] = v.size() ;
}
for ( auto u : edge[nod] )
{
if ( u.first != p)
{
dfs (u.first, nod );
v.push_back(nod);
}
}
tout[nod] = v.size();
}
long long jmp[ 600005 ][ 19] ;
void dfs4(int nod, int p )
{
for ( auto u :edge[nod])
{
if ( u.first != p )
{
rev[u.first] = rev[nod] + u.second;
dfs4(u.first,nod);
}
}
}
void dfs2 ( int nod, int p )
{
for ( auto u : edge[nod])
{
if ( u.first != p )
{
dfs2 (u.first, nod);
}
}
if (shop [nod] == 1 )
ext[nod] = rev[nod];
else
ext[nod] = 1e18 ;
for ( auto u : edge[nod] )
{
if ( u.first != p )
{
ext[nod] = min ( ext[nod], ext[u.first]);
}
}
}
long long mag[600005][18];
void dfs3 ( int nod, int p )
{
jmp[nod][0] = p;
mag[nod][0] = ext[nod];
for ( int k = 1 ; k <= 18 ; k ++ )
{
jmp[nod][k] = jmp[jmp[nod][k-1]][k-1];
mag[nod][k] = min(mag[nod][k-1], mag[jmp[nod][k-1]][k-1]);
}
for ( auto u : edge[nod] )
{
if (u .first != p)
dfs3(u.first,nod);
}
}
vector<pair<int,int>> qr;
long long jumps( int nod, int p )
{
long long ans = 1e18 ;
long long u = nod ;
for ( int k = 0 ; k <= 19 ; k ++ )
{
if ( p & ( 1 << k ) )
{
ans = min ( ans , mag[u][k]);
u = jmp[u][k];
}
}
return ans + rev[nod];
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> s >> q >> e;
for ( int i =1; i < n ; i ++ )
{
int a, b,c;
cin >> a >> b>>c;
edge[a].push_back({b,c});
edge[b].push_back({a,c});
qr.push_back({a,b});
}
for( int i = 1; i <= s; i ++ )
{
int val;
cin >> val ;
shop [val] = 1;
}
dfs(e,0);
dfs4(e,0);
dfs2(e,0);
for ( int i = 1; i <= n ; i ++ )
ext [i] -= 2 * rev[i];
dfs3(e,0);
//cout << mag[2][0] << " " << " hsb" << '\n';
for ( int i = 1; i <= q; i ++ )
{
int l, r;
cin >> l >> r ;
l -- ;
int a = qr[l].first;
int b = qr[l].second;
int tg ;
if ( tin[a] <= tin[b] && tout[a] >= tout[b])
tg = b ;
else
tg = a;
if ( tin[tg] <= tin[r] && tout[tg] >= tout[r])
{
}
else
{
cout << "escaped" << '\n';
continue ;
}
int c = depth[tg] - depth[r];
long long ans = jumps(r,c) ;
if ( ans >= 1e16 )
{
cout << "oo" << '\n';
continue;
}
cout << ans << '\n';
}
return 0;
}
Compilation message
valley.cpp: In function 'void dfs3(int, int)':
valley.cpp:80:21: warning: iteration 17 invokes undefined behavior [-Waggressive-loop-optimizations]
80 | mag[nod][k] = min(mag[nod][k-1], mag[jmp[nod][k-1]][k-1]);
| ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:77:25: note: within this loop
77 | for ( int k = 1 ; k <= 18 ; k ++ )
| ~~^~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
11 ms |
33628 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
11 ms |
33628 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
10 ms |
33736 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
11 ms |
33628 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
