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