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| #include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
const int maxn = 1e+5 + 1;
struct edge {
int to, nxt;
}e[maxn << 1];
int n, ptr, m, lnk[maxn];
int dfn[maxn], top[maxn], siz[maxn], mxson[maxn];
int dep[maxn], fa[maxn], cnt, ans, tot;
int val[maxn << 1], xx[maxn << 1], yy[maxn << 1], vpr;
pii arr[maxn];
struct Heap {
priority_queue<int> a, d;
inline void ps(int x) {
a.push(x);
}
inline void de(int x) {
d.push(x);
}
inline int tp() {
while (!d.empty() && a.top() == d.top()) a.pop(), d.pop();
return a.empty() ? -1 : a.top();
}
}s[maxn << 2];
void dfs(int x, int f) {
dep[x] = dep[f] + 1;
siz[x] = 1;
fa[x] = f;
for (int p = lnk[x]; p; p = e[p].nxt) {
int y = e[p].to;
if (y == f) continue;
dfs(y, x);
siz[x] += siz[y];
if (siz[y] >= siz[mxson[x]]) mxson[x] = y;
}
}
void dfs2(int x, int init) {
top[x] = init;
dfn[x] = ++cnt;
if (!mxson[x]) return;
dfs2(mxson[x], init);
for (int p = lnk[x]; p; p = e[p].nxt) {
int y = e[p].to;
if (y == fa[x] || y == mxson[x]) continue;
dfs2(y, y);
}
}
void update(int cur, int l, int r, int L, int R, int v, int t) {
if (l == L && r == R) {
if (t) s[cur].ps(v);
else s[cur].de(v);
return;
}
int mid = (l + r) >> 1;
if (R <= mid) update(cur << 1, l, mid, L, R, v, t);
else if (L > mid) update(cur << 1|1, mid + 1, r, L, R, v, t);
else {
update(cur << 1, l, mid, L, mid, v, t);
update(cur << 1|1, mid + 1, r, mid + 1, R, v, t);
}
}
void query(int cur, int l, int r, int p) {
ans = max(ans, s[cur].tp());
if (l == r) return;
int mid = (l + r) >> 1;
if (p <= mid) query(cur << 1, l, mid, p);
else query(cur << 1|1, mid + 1, r, p);
}
void modify(int x, int y, int v, int t) {
tot = 0;
while (top[x] != top[y]) {
if (dep[top[x]] < dep[top[y]]) swap(x, y);
arr[++tot] = make_pair(dfn[top[x]], dfn[x]);
x = fa[top[x]];
}
if (dep[x] > dep[y]) swap(x, y);
arr[++tot] = make_pair(dfn[x], dfn[y]);
sort(arr + 1, arr + 1 + tot);
arr[0] = make_pair(0, 0); arr[tot + 1] = make_pair(n + 1, n + 1);
for (int i = 0; i <= tot; ++i) {
int l = arr[i].second + 1, r = arr[i + 1].first - 1;
if (l <= r)
update(1, 1, n, l, r, v, t);
}
}
inline void add(int bgn, int end) {
e[++ptr] = (edge){end, lnk[bgn]};
lnk[bgn] = ptr;
}
inline int rd() {
register int x = 0, c = getchar();
while (!isdigit(c)) c = getchar();
while (isdigit(c)) x = x * 10 + (c ^ 48), c = getchar();
return x;
}
int main() {
n = rd(); m = rd();
int u, v;
for (int i = 1; i < n; ++i) {
u = rd(); v = rd();
add(u, v);
add(v, u);
}
dfs(1, 0);
dfs2(1, 1);
int opt, vle;
while (m--) {
vpr++;
opt = rd();
if (opt == 0) {
u = rd(); v = rd(); vle = rd();
val[vpr] = vle;
xx[vpr] = u; yy[vpr] = v;
modify(u, v, vle, 1);
} else if (opt == 1) {
u = rd();
modify(xx[u], yy[u], val[u], 0);
} else {
u = rd(); ans = -1;
query(1, 1, n, dfn[u]);
printf("%d\n", ans);
}
}
return 0;
}
|
