玄关
by Lightning_Creeper @ 2023-08-20 16:41:56
在调了，等会。
by _HyperV_ @ 2023-08-20 16:43:28
浅改了一下，有什么不懂的可以来问。
强烈建议您阅读 **OI Wiki** 上的 [树链剖分](https://oi.wiki/graph/hld/) 页面
```cpp
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 1e5+5;
int n, m, r;
int p;
struct Node {
int l, r;
int lz, sum;
} tr[MAXN * 4];
int v[MAXN];
vector<int> G[MAXN];
int fa[MAXN], dep[MAXN], siz[MAXN], son[MAXN], top[MAXN], dfn[MAXN], val[MAXN], num;
void lazy(int k, int v) {
if (!v)
return;
tr[k].lz += v;
tr[k].lz %= p;
tr[k].sum = (tr[k].sum + 1LL * v % p * (tr[k].r - tr[k].l + 1) % p) % p;
}
void pushup(int k) {
tr[k].sum = (tr[k * 2].sum + tr[k * 2 + 1].sum) % p;
}
void pushdown(int k) {
lazy(k * 2, tr[k].lz);
lazy(k * 2 + 1, tr[k].lz);
tr[k].lz = 0;
}
void build(int k, int l, int r) {
tr[k].l = l, tr[k].r = r;
if (l == r) {
tr[k].sum = val[l];
return;
}
int md = l + r >> 1;
build(k * 2, l, md);
build(k * 2 + 1, md + 1, r);
pushup(k);
}
void update(int k, int l, int r, int v) {
if (tr[k].r < l || r < tr[k].l)
return;
if (tr[k].l >= l && tr[k].r <= r)
return lazy(k, v);
pushdown(k);
int lc = k * 2, rc = lc + 1;
update(lc, l, r, v); update(rc, l, r, v);
pushup(k);
}
int query(int k, int l, int r) {
if (tr[k].r < l || r < tr[k].l)
return 0;
if (tr[k].l >= l && tr[k].r <= r)
return tr[k].sum;
pushdown(k);
int lc = k * 2, rc = lc + 1;
return (query(lc, l, r) + query(rc, l, r)) % p;
}
void dfs1(int u,int f) {
siz[u] = 1, dep[u] = dep[fa[u] = f] + 1;
for (int v : G[u]) {
if (v == fa[u]) continue;
dfs1(v, u);
siz[u] += siz[v];
if (siz[v] > siz[son[u]])
son[u] = v;
}
}
void dfs2(int u, int t) {
// cerr << u << " " << t<< '\n';
top[u] = t;
dfn[u] = ++num;
val[num] = v[u];
if (!son[u]) return;
dfs2(son[u], t);
for (int v : G[u])
if (v != son[u] && v != fa[u])
dfs2(v, v);
}
void update_path(int x, int y, int z) {
while (top[x] != top[y]) {
if (dep[top[x]] < dep[top[y]])
swap(x, y);
update(1, dfn[top[x]], dfn[x], z);
x = fa[top[x]];
}
if(dep[x] > dep[y])
swap(x, y);
update(1, dfn[x], dfn[y], z);
}
int query_path(int x, int y) {
int res = 0;
while (top[x] != top[y]) {
//cerr <<x << " "<<y<<'\n';
//cerr <<top[x]<<" " << top[y] << '\n';
if (dep[top[x]] < dep[top[y]])
swap(x, y);
res = (res + query(1, dfn[top[x]], dfn[x])) % p;
x = fa[top[x]];
}
if (dep[x] > dep[y])
swap(x, y);
res = (res + query(1, dfn[x], dfn[y])) % p;
return res;
}
void update_tree(int x, int z) {
update(1, dfn[x], dfn[x] + siz[x] - 1, z);
}
int query_tree(int x) {
return query(1, dfn[x], dfn[x] + siz[x] - 1);
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n >> m >> r >> p;
for (int i = 1; i <= n; i++) {
cin >> v[i];
v[i] %= p;
}
for (int i = 1; i <= n - 1; i++) {
int x, y;
cin >> x >> y;
G[x].push_back(y);
G[y].push_back(x);
}
dfs1(r, 0);
dfs2(r, r);
build(1, 1, n);
for (int i = 1; i <= m; i++) {
// cerr << "fuck\n";
int opt, x, y;
int z;
cin >> opt;
switch (opt) {
case 1:
cin >> x >> y >> z;
update_path(x, y, z);
break;
case 2:
cin >> x >> y;
cout << query_path(x, y) << endl;
break;
case 3:
cin >> x >> z;
update_tree(x, z);
break;
case 4:
cin >> x;
cout << query_tree(x) << endl;
break;
}
}
return 0;
}
```
by _HyperV_ @ 2023-08-20 18:19:13
@[Lightning_Creeper](/user/386547)
by _HyperV_ @ 2023-08-20 18:19:34
我的 `update_path` 和 `query_path` 就是照着 $\text{OIwiki}$ 写的。
by Lightning_Creeper @ 2023-08-21 08:59:00