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OI-codes/Codeforces/1675/F/F.cpp

59 lines
981 B
C++

#include <iostream>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 2e5 + 5;
int t, n, k, x, y, a[N], siz[N], dis[N], ans;
std::vector<int> g[N];
void dfs(int u, int fa) {
for (int v : g[u]) {
if (v == fa) continue;
dis[v] = dis[u] + 1;
dfs(v, u);
siz[u] += siz[v];
ans += !!siz[v];
}
}
int main() {
std::ios::sync_with_stdio(false);
cin >> t;
while (t--) {
ans = 0;
cin >> n >> k >> x >> y;
siz[y] = 1;
for (int i = 1; i <= k; i++) {
cin >> a[i];
siz[a[i]] = 1;
}
for (int i = 1, u, v; i < n; i++) {
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
dfs(x, -1);
cout << ans * 2 - dis[y] << endl;
for (int i = 1; i <= n; i++) {
g[i].clear();
dis[i] = siz[i] = 0;
}
}
return 0;
}