Solution - P3384 【模板】重链剖分/树链剖分

糖丸了，写 Segment Tree 维护区间和不加区间长度。

思路

简单树剖板子，没什么好说的。（虽然蒟蒻第一次写树剖）

不是我是多久没写线段树了

代码

#include <bits/stdc++.h>
#define rint register int
#define rllong register long long
#define llong long long
#define N 100005
using namespace std;

int n, q, root, mod;
int val[N<<2], tag[N<<2];
int a[N], raw[N];
#define ls(x) (x<<1)
#define rs(x) (x<<1|1)
#define mid (l+r>>1)
#define len (r-l+1)
#define pushup(x) (val[x] = (val[ls(x)]+val[rs(x)])%mod)

inline void pushdown(rint x, rint l, rint r){
	if(!tag[x]) return;
	val[ls(x)] += tag[x]*(mid-l+1), tag[ls(x)] += tag[x];
	val[rs(x)] += tag[x]*(r-mid)  , tag[rs(x)] += tag[x];
	tag[x] = 0;
	return;
}

inline void build(rint x, rint l, rint r){
	if(l == r){
		val[x] = raw[l]%mod;
		return;
	}
	build(ls(x), l, mid  );
	build(rs(x), mid+1, r);
	pushup(x);
	return;
}

inline void modify(rint x, rint L, rint R, rint l, rint r, rint k){
	if(L <= l && R >= r){
		val[x] += k*len, tag[x] += k;
		return;
	}
	pushdown(x, l, r);
	if(L <= mid) modify(ls(x), L, R, l, mid,   k);
	if(R >  mid) modify(rs(x), L, R, mid+1, r, k);
	pushup(x);
	return;
}

inline int query(rint x, rint L, rint R, rint l, rint r){
	if(L <= l && R >= r) return val[x];
	pushdown(x, l, r);
	rint ans = 0;
	if(L <= mid) ans += query(ls(x), L, R, l, mid  );
	if(R >  mid) ans += query(rs(x), L, R, mid+1, r);
	return ans%mod;
}

int dfn[N], siz[N], dep[N], dfcnt;
int top[N], son[N], fa [N];
int to[N<<1], nxt[N<<1], head[N], gsiz = 1;
#define mkarc(u,v) (++gsiz,to[gsiz]=v,nxt[gsiz]=head[u],head[u]=gsiz)

inline void dfs1(rint u){
	dep[u] = dep[fa[u]]+1, siz[u] = 1;
	for(rint i = head[u]; i; i = nxt[i]){
		rint v = to[i];
		if(v == fa[u]) continue;
		fa[v] = u;
		dfs1(v);
		if(siz[v] > siz[son[u]]) son[u] = v;
		siz[u] += siz[v];
	}
	return;
}

inline void dfs2(rint u){
	dfn[u] = ++dfcnt, raw[dfn[u]] = a[u];
	if(!son[u]) return;
	top[son[u]] = top[u];
	dfs2(son[u]);
	for(rint i = head[u]; i; i = nxt[i]){
		rint v = to[i];
		if(v == fa[u] || v == son[u]) continue;
		top[v] = v;
		dfs2(v);
	}
	return;
}

inline void modifylink(rint u, rint v, rint k){
	while(top[u] != top[v]){
		if(dep[top[u]] > dep[top[v]]) swap(u, v);
		modify(1, dfn[top[v]], dfn[v], 1, n, k);
		v = fa[top[v]];
	}
	if(dep[u] > dep[v]) swap(u, v);
	modify(1, dfn[u], dfn[v], 1, n, k);
	return;
}

inline int querylink(rint u, rint v){
	rint ans = 0;
	while(top[u] != top[v]){
		if(dep[top[u]] > dep[top[v]]) swap(u, v);
		ans = (ans+query(1, dfn[top[v]], dfn[v], 1, n))%mod;
		v = fa[top[v]];
	}
	if(dep[u] > dep[v]) swap(u, v);
	ans = (ans+query(1, dfn[u], dfn[v], 1, n));
	return ans%mod;
}

int main(){
	scanf("%d %d %d %d", &n, &q, &root, &mod);
	for(rint i = 1; i <= n; ++i) scanf("%d", &a[i]);
	for(rint i = 1; i <  n; ++i){
		rint u, v;
		scanf("%d %d", &u, &v);
		mkarc(u, v), mkarc(v, u);
	}
	top[root] = root;
	dfs1(root);
	dfs2(root);
	build(1, 1, n);
	while(q--){
		rint op, u, v, k;
		scanf("%d", &op);
		if(op == 1){
			scanf("%d %d %d", &u, &v, &k);
			k %= mod;
			modifylink(u, v, k);
		}
		else if(op == 2){
			scanf("%d %d", &u, &v);
			printf("%d\n", (querylink(u, v))%mod);
		}
		else if(op == 3){
			scanf("%d %d", &u, &k);
			modify(1, dfn[u], dfn[u]+siz[u]-1, 1, n, k);
		}
		else{
			scanf("%d", &u);
			printf("%d\n", query(1, dfn[u], dfn[u]+siz[u]-1, 1, n)%mod);
		}
	}
	return 0;
}