/*
Mayoeba Yabureru
*/
//#include "closing.h"
#include<bits/stdc++.h>
using namespace std;
int max_score(int n, int x, int y, long long k, vector<int> U, vector<int> V, vector<int> W) {
x ++, y ++;
vector dis(n + 1, vector<long long>(2));
vector<vector<pair<int, long long>>> gr(n + 1);
for (int i = 0; i < n - 1; i ++) {
int u = U[i] + 1, v = V[i] + 1, w = W[i];
gr[u].push_back({v, w});
gr[v].push_back({u, w});
}
function<void(int, int, int)> dfs = [&] (int v, int p, int wt) {
for (auto [u, w] : gr[v]) {
if (u == p) continue;
dis[u][wt] = dis[v][wt] + w;
dfs(u, v, wt);
}
};
dfs(x, 0, 0), dfs(y, 0, 1);
vector<int> vc, path, onpath(n + 1);
function<void(int, int)> go = [&] (int v, int p) {
vc.push_back(v);
if (v == y) path = vc;
for (auto [u, w] : gr[v]) {
if (u == p) continue;
go(u, v);
}
vc.pop_back();
};
go(x, 0);
long long minstart = 0, mn = 1e16;
for (auto mid : path) {
onpath[mid] = 1;
if (max(dis[mid][0], dis[mid][1]) < mn) {
mn = max(dis[mid][0], dis[mid][1]);
minstart = mid;
}
}
multiset<pair<long long, int>> ms;
vector<int> did(n + 1);
int ans = 0;
function f = [&] {
multiset<pair<long long, int>> s;
for (int i = 1; i <= n; i ++) {
if (did[i]) continue;
s.insert({dis[i][0], i});
s.insert({dis[i][1], i});
}
int cnt = 0;
while (s.size()) {
auto [x, y] = *s.begin();
s.erase(s.begin());
if (did[y]) continue;
if (x > k) break;
k -= x;
did[y] = 1;
cnt ++;
}
return cnt;
};
long long kk = k;
ans = f();
for (int i = 1; i <= n; i ++) did[i] = 0;
int cnt = 2;
k = kk - mn;
for (auto x : path) {
did[x] = 1;
if (x == minstart) break;
cnt ++;
k -= dis[x][0];
}
for (int i = path.size() - 1; i >= 0; i --) {
int x = path[i];
did[x] = 1;
if (x == minstart) break;
cnt ++;
k -= dis[x][1];
}
if (k < 0) return ans;
for (int i = 1; i <= n; i ++) {
if (i == minstart) continue;
if (onpath[i] == 0) ms.insert({max(dis[i][0], dis[i][1]), i});
else ms.insert({abs(dis[i][0] - dis[i][1]), i});
}
while (ms.size()) {
vector<int> odid = did;
long long kk = k;
ans = max(ans, cnt + f());
did = odid;
k = kk;
auto [x, y] = *ms.begin();
ms.erase(ms.begin());
if (x > k) break;
k -= x;
did[y] = 1;
if (onpath[y] == 0) cnt += 2;
else cnt ++; // this is wrong but in the case where the tree is linear
}
return ans;
}
/*
1
7 0 2 10
0 1 2
0 3 3
1 2 4
2 4 2
2 5 5
5 6 3
*/
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int T = 1;
cin >> T;
while (T --) {
int n, x, y;
long long k;
cin >> n >> x >> y >> k;
vector<int> U(n - 1), V(n - 1), W(n - 1);
for (int i = 0; i < n - 1; i ++) cin >> U[i] >> V[i] >> W[i];
cout << max_score(n, x, y, k, U, V, W) << endl;
}
}
Compilation message
/usr/bin/ld: /tmp/cc5Llw0e.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccxylPlh.o:closing.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status
