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#include <bits/stdc++.h>
#define N 200005
using namespace std;
struct edge {
int t, col, next;
} e[N * 2];
int ecnt, head[N];
void addedge(int f, int t, int c) {
e[++ecnt] = (edge){t, c, head[f]};
head[f] = ecnt;
e[++ecnt] = (edge){f, c, head[t]};
head[t] = ecnt;
}
int n, m, l, r;
int val[N];
int sz[N], vis[N];
int cen, ans;
void findc(int u, int fr, int tot) {
sz[u] = 1;
int mx = 0;
for (int i = head[u]; i; i = e[i].next) {
if (e[i].t != fr && vis[e[i].t] != 1) {
findc(e[i].t, u, tot);
sz[u] += sz[e[i].t];
mx = max(mx, sz[e[i].t]);
}
}
if (max(mx, tot - sz[u]) <= tot / 2) cen = u;
}
int deep[N];
void getd(int u, int fr) {
deep[u] = 1;
sz[u] = 1;
for (int i = head[u]; i; i = e[i].next) {
if (vis[e[i].t] == 0 && e[i].t != fr) {
getd(e[i].t, u);
deep[u] = max(deep[e[i].t] + 1, deep[u]);
sz[u] += sz[e[i].t];
}
}
}
edge bd[N];
vector<edge> v[N];
int sor[N], scnt;
bool cmp(int a, int b) { return deep[bd[a].t] < deep[bd[b].t]; }
bool cmpe(edge a, edge b) { return deep[a.t] < deep[b.t]; }
int best1[N], best2[N], b1sz, b2sz;
int buf[N], bsz;
void DFS(int u, int fr, int frc, int v, int num) {
bsz = max(bsz, num);
buf[num] = max(buf[num], v);
if (num >= l && num <= r) ans = max(ans, v);
for (int i = head[u]; i; i = e[i].next) {
if (vis[e[i].t] == 0 && e[i].t != fr) {
if (e[i].col == frc)
DFS(e[i].t, u, frc, v, num + 1);
else
DFS(e[i].t, u, e[i].col, v + val[e[i].col], num + 1);
}
}
}
int vi[N], ti[N];
int headx, tail;
void add(int vv, int tnow, int tt) {
while (headx > tail && vi[headx] <= vv) headx--;
while (headx > tail && ti[tail + 1] <= tnow) tail++;
vi[++headx] = vv;
ti[headx] = tt;
}
long long query(int tnow) {
while (headx > tail && ti[tail + 1] <= tnow) tail++;
return headx > tail ? vi[tail + 1] : -2e9;
}
void solve(int u, int totsz) {
vis[u] = 1;
if (totsz < l) return;
for (int i = head[u]; i; i = e[i].next)
if (vis[e[i].t] != 1) getd(e[i].t, u);
for (int i = head[u]; i; i = e[i].next)
if (vis[e[i].t] != 1) {
v[e[i].col].push_back(e[i]);
if (v[e[i].col].size() == 1) sor[++scnt] = e[i].col;
if (bd[e[i].col].t == 0 || deep[e[i].t] >= deep[bd[e[i].col].t])
bd[e[i].col] = e[i];
}
sort(sor + 1, sor + scnt + 1, cmp);
for (int i = 1; i <= scnt; i++) {
int c = bd[sor[i]].col;
sort(v[c].begin(), v[c].end(), cmpe);
for (int j = 0; j < v[c].size(); j++) {
DFS(v[c][j].t, u, v[c][j].col, val[v[c][j].col], 1);
int l1 = l - 1, r1 = r - 1;
headx = tail = 0;
for (int k = min(b2sz, r1); k >= max(l1, 1); k--)
add(best2[k], -k, -(k - (r - l + 1)));
for (int k = 1; k <= bsz && r1 >= 1; k++, l1--, r1--) {
if (l1 >= 1 && l1 <= b2sz)
add(best2[l1], -l1, -l1 + (r - l + 1));
ans = max(ans * 1ll, query(-l1) + buf[k] - val[c]);
}
for (int k = 1; k <= bsz; k++)
best2[k] = max(best2[k], buf[k]), buf[k] = -2e9;
b2sz = max(b2sz, bsz);
bsz = 0;
}
int l1 = l - 1, r1 = r - 1;
headx = tail = 0;
for (int k = min(b1sz, r1); k >= max(l1, 1); k--)
add(best1[k], -k, -(k - (r - l + 1)));
for (int k = 1; k <= b2sz && r1 >= 1; k++, l1--, r1--) {
if (l1 >= 1 && l1 <= b1sz) add(best1[l1], -l1, -l1 + (r - l + 1));
ans = max(ans * 1LL, query(-l1) + best2[k]);
}
for (int k = 1; k <= b2sz; k++)
best1[k] = max(best1[k], best2[k]), best2[k] = -2e9;
b1sz = max(b1sz, b2sz);
b2sz = 0;
}
for (int i = head[u]; i; i = e[i].next)
if (vis[e[i].t] != 1)
v[e[i].col].clear(), bd[e[i].col] = (edge){0, 0, 0};
scnt = 0;
for (int i = 1; i <= b1sz; i++) best1[i] = -2e9;
for (int i = 1; i <= b2sz; i++) best2[i] = -2e9;
b1sz = b2sz = 0;
for (int i = head[u]; i; i = e[i].next) {
if (vis[e[i].t] == 0) {
int tot = sz[e[i].t];
findc(e[i].t, u, tot);
solve(cen, tot);
}
}
}
void readin() {
scanf("%d%d%d%d", &n, &m, &l, &r);
for (int i = 1; i <= m; i++) scanf("%d", &val[i]);
for (int i = 2; i <= n; i++) {
int f, t, c;
scanf("%d%d%d", &f, &t, &c);
addedge(f, t, c);
}
for (int i = 1; i <= n; i++) best1[i] = best2[i] = buf[i] = -2e9;
best1[0] = best2[0] = buf[0] = 0;
ans = -2e9;
}
int main() {
freopen("journey.in", "r", stdin);
freopen("journey.out", "w", stdout);
readin();
findc(1, 0, n);
solve(cen, n);
cout << ans << endl;
return 0;
}
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