0
1
mirror of https://git.sb/baoshuo/OI-codes.git synced 2024-12-25 16:52:00 +00:00
OI-codes/Luogu/P2486/P2486.cpp
2021-11-29 19:17:26 +08:00

175 lines
3.9 KiB
C++

#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int n, m, u, v, c, color[N];
char op;
vector<int> g[N];
// Heavy Path Decomposition
int cnt, dep[N], id[N], siz[N], fa[N], son[N], top[N], w[N];
void dfs1(int, int);
void dfs2(int u, int t);
void modify_path(int, int, int);
int query_path(int, int);
// Segment Tree
void pushup(int);
void pushdown(int);
void build(int, int, int);
void modify(int, int, int, int);
int query_sum(int, int, int);
int query_color(int, int);
int main() {
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> color[i];
}
for (int i = 1; i < n; i++) {
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
dfs1(1, 0);
dfs2(1, 1);
build(1, 1, n);
while (m--) {
cin >> op >> u >> v;
if (op == 'C') {
cin >> c;
modify_path(u, v, c);
} else {
cout << query_path(u, v) << endl;
}
}
return 0;
}
// === Heavy Path Decomposition ===
void dfs1(int u, int f) {
dep[u] = dep[f] + 1;
fa[u] = f;
siz[u] = 1;
for (int v : g[u]) {
if (v == f) continue;
dfs1(v, u);
siz[u] += siz[v];
if (siz[son[u]] < siz[v]) son[u] = v;
}
}
void dfs2(int u, int t) {
id[u] = ++cnt;
w[cnt] = color[u];
top[u] = t;
if (!son[u]) return;
dfs2(son[u], t);
for (int v : g[u]) {
if (v == fa[u]) continue;
if (v == son[u]) continue;
dfs2(v, v);
}
}
void modify_path(int u, int v, int c) {
while (top[u] != top[v]) {
if (dep[top[u]] < dep[top[v]]) swap(u, v);
modify(1, id[top[u]], id[u], c);
u = fa[top[u]];
}
if (dep[u] < dep[v]) swap(u, v);
modify(1, id[v], id[u], c);
}
int query_path(int u, int v) {
int res = 0;
while (top[u] != top[v]) {
if (dep[top[u]] < dep[top[v]]) swap(u, v);
res += query_sum(1, id[top[u]], id[u]);
res -= (query_color(1, id[top[u]]) == query_color(1, id[fa[top[u]]]));
u = fa[top[u]];
}
if (dep[u] < dep[v]) swap(u, v);
res += query_sum(1, id[v], id[u]);
return res;
}
// === Segment Tree ===
struct node {
int l, r, s, d, lc, rc;
node()
: l(0), r(0), s(0), d(0), lc(0), rc(0) {}
node(int _l, int _r)
: l(_l), r(_r), s(0), d(0), lc(0), rc(0) {}
} tr[N << 2];
inline void pushup(int u) {
tr[u].s = tr[u << 1].s + tr[u << 1 | 1].s - (tr[u << 1].rc == tr[u << 1 | 1].lc);
tr[u].lc = tr[u << 1].lc;
tr[u].rc = tr[u << 1 | 1].rc;
}
inline void pushdown(int u) {
auto &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1];
if (!tr[u].d) return;
left.d = right.d = root.d;
left.lc = left.rc = right.lc = right.rc = root.d;
left.s = right.s = 1;
root.d = 0;
}
void build(int u, int l, int r) {
tr[u] = node(l, r);
if (l == r) {
tr[u].lc = tr[u].rc = w[l];
tr[u].s = 1;
return;
}
int mid = l + r >> 1;
build(u << 1, l, mid);
build(u << 1 | 1, mid + 1, r);
pushup(u);
}
void modify(int u, int l, int r, int c) {
if (l <= tr[u].l && tr[u].r <= r) {
tr[u].d = tr[u].lc = tr[u].rc = c;
tr[u].s = 1;
return;
}
pushdown(u);
int mid = tr[u].l + tr[u].r >> 1;
if (l <= mid) modify(u << 1, l, r, c);
if (r > mid) modify(u << 1 | 1, l, r, c);
pushup(u);
}
int query_sum(int u, int l, int r) {
if (l <= tr[u].l && tr[u].r <= r) {
return tr[u].s;
}
int mid = tr[u].l + tr[u].r >> 1;
int res = 0;
pushdown(u);
if (l <= mid) res += query_sum(u << 1, l, r);
if (r > mid) res += query_sum(u << 1 | 1, l, r);
if (l <= mid && r > mid) res -= (tr[u << 1].rc == tr[u << 1 | 1].lc);
return res;
}
int query_color(int u, int x) {
if (tr[u].l == x && tr[u].r == x) {
return tr[u].lc;
}
int mid = tr[u].l + tr[u].r >> 1;
pushdown(u);
if (x <= mid) return query_color(u << 1, x);
return query_color(u << 1 | 1, x);
}