SP6779 GSS7 - Can you answer these queries VII(线段树，树链剖分)

水题，只是坑点多，\(tag\)为\(0\)时可能也要\(pushdown\)，所以要\(bool\)标记是否需要。最后树链剖分询问时注意线段有向！！！

#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <numeric>
#define R(a,b,c) for(register int a = (b); a <= (c); ++a)
#define nR(a,b,c) for(register int a = (b); a >= (c); --a)
#define Swap(a,b) ((a) ^= (b) ^= (a) ^= (b))
#define MP make_pair
#ifdef QWQ
#define D_e_Line printf("\n------\n")
#define D_e(x) cerr << (#x) << " " << x << endl
#define C_e(x) cout << (#x) << " " << x << endl
#define FileOpen() freopen("in.txt", "r", stdin)
#define FileSave() freopen("out.txt", "w", stdout)
#define Pause() system("pause")
#include <cassert>
#define PASS fprintf(stderr, "Passing [%s] in LINE %d\n",__FUNCTION__,__LINE__)
#else
#define D_e_Line
#define D_e(x)
#define C_e(x)
#define FileOpen()
#define FileSave()
#define Pause()
#define PASS
#endif
using namespace std;
struct FastIO {
	template<typename ATP> inline FastIO& operator >> (ATP &x) {
		x = 0; int sign = 1; char c;
		for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-') sign = -1;
		while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();
		if(sign == -1) x = -x;
		return *this;
	}
} io;
template<typename ATP> inline ATP Max(ATP x, ATP y) {
	return x > y ? x : y;
}
template<typename ATP> inline ATP Min(ATP x, ATP y) {
	return x < y ? x : y;
}
template<typename ATP> inline ATP Abs(ATP x) {
	return x < 0 ? -x : x;
}
#include <vector>
const int N = 2e5 + 7;
struct Edge {
	int nxt, pre;
} e[N << 1];
int head[N], cntEdge;
inline void add(int u, int v) {
	e[++cntEdge] = (Edge){ head[u], v}, head[u] = cntEdge;
}
int fa[N], son[N], siz[N], dep[N], dfn[N], dfnIdx, top[N], rnk[N], val[N], n;
void DFS_First(int u, int father) {
	dep[u] = dep[father] + 1, fa[u] = father, siz[u] = 1;
	for(register int i = head[u]; i; i = e[i].nxt){
		int v = e[i].pre;
		if(v == father) continue;
		DFS_First(v, u);
		siz[u] += siz[v];
		if(siz[v] > siz[son[u]]) son[u] = v;
	}
}
void DFS_Second(int u, int Tp) {
	top[u] = Tp, dfn[u] = ++dfnIdx, rnk[dfnIdx] = u;
	if(!son[u]) return;
	DFS_Second(son[u], Tp);
	for(register int i = head[u]; i; i = e[i].nxt){
		int v = e[i].pre;
		if(v != fa[u] && v != son[u]) DFS_Second(v, v);
	}
}
struct Seg {
	int sum, val, pre, suf, tag;
	bool flag;
	Seg() {sum = val = pre = suf = tag = flag = 0;}
	Seg operator + (const Seg &b) const {
		Seg c;
		c.sum = sum + b.sum;
		c.val = Max(Max(val, b.val), suf + b.pre);
		c.pre = Max(pre, sum + b.pre);
		c.suf = Max(b.suf, b.sum + suf);
		return c;
	}
} t[N << 2];
#define ls rt << 1
#define rs rt << 1 | 1
#define lson rt << 1, l, mid
#define rson rt << 1 | 1, mid + 1, r
inline void Pushup(int &rt) {
	t[rt] = t[ls] + t[rs];
}
inline void Pushdown(int &rt, int l, int mid, int r) {
	t[ls].sum = (mid - l + 1) * t[rt].tag;
	t[rs].sum = (r - mid) * t[rt].tag;
	t[ls].pre = t[ls].val = t[ls].suf = Max(t[ls].sum, 0);
	t[rs].pre = t[rs].val = t[rs].suf = Max(t[rs].sum, 0);
	t[ls].flag = t[rs].flag = true;
	t[ls].tag = t[rs].tag = t[rt].tag;
	t[rt].tag = 0;
	t[rt].flag = false;
}
void Build(int rt, int l, int r) {
	if(l == r){
		t[rt].sum = val[rnk[l]];
		t[rt].val = t[rt].pre = t[rt].suf = Max(t[rt].sum, 0);
		return;
	}
	int mid = (l + r) >> 1;
	Build(lson), Build(rson);
	Pushup(rt);
}
void Updata(int rt, int l, int r, int L, int R, int w) {
	if(L <= l && r <= R){
		t[rt].sum = (r - l + 1) * w;
		t[rt].pre = t[rt].suf = t[rt].val = Max(t[rt].sum, 0);
		t[rt].tag = w;
		t[rt].flag = true;
		return;
	}
	int mid = (l + r) >> 1;
	if(t[rt].flag) Pushdown(rt, l, mid, r);
	if(L <= mid) Updata(lson, L, R, w);
	if(R > mid) Updata(rson, L, R, w);
	Pushup(rt);
}
Seg Query(int rt, int l, int r, int L, int R) {
	if(L <= l && r <= R) return t[rt];
	int mid = (l + r) >> 1;
	if(t[rt].flag) Pushdown(rt, l, mid, r);
	Seg s;
	if(L <= mid) s = Query(lson, L, R);
	if(R > mid) s = s + Query(rson, L, R);
	return s;
}
inline void Updata(int x, int y, int w) {
	while(top[x] != top[y]){
		if(dep[top[x]] < dep[top[y]]) Swap(x, y);
		Updata(1, 1, n, dfn[top[x]], dfn[x], w);
		x = fa[top[x]];
	}
	if(dep[x] < dep[y]) Swap(x, y);
	Updata(1, 1, n, dfn[y], dfn[x], w);
}
//inline int Query(int x, int y) {
//	Seg s;
//	while(top[x] != top[y]){
//		if(dep[top[x]] < dep[top[y]]) Swap(x, y);
//		s = s + Query(1, 1, n, dfn[top[x]], dfn[x]);
//		x = fa[top[x]];
//	}
//	if(dep[x] < dep[y]) Swap(x, y);
//	Swap(s.suf, s.pre);
//	return (s + Query(1, 1, n, dfn[y], dfn[x])).val;
//}
inline int Query(int x, int y) {
	Seg L, R;
	while(top[x] != top[y]){
		if(dep[top[x]] < dep[top[y]]){
			R = Query(1, 1, n, dfn[top[y]], dfn[y]) + R;
			y = fa[top[y]];
		}
		else{
			L = Query(1, 1, n, dfn[top[x]], dfn[x]) + L;
			x = fa[top[x]];
		}
	}
	if(dep[x] > dep[y]){
		L = Query(1, 1, n, dfn[y], dfn[x]) + L;
	}
	else{
		R = Query(1, 1, n, dfn[x], dfn[y]) + R;
	}
	Swap(L.pre, L.suf);
	return (L + R).val;
}
int main() {
//FileOpen();
//FileSave();
	io >> n;
	R(i,1,n) io >> val[i];
	R(i,2,n){
		int u, v;
		io >> u >> v;
		add(u, v);
		add(v, u);
	}
	DFS_First(1, 0);
	DFS_Second(1, 1);
	Build(1, 1, n);
	int m;
	io >> m;
	while(m--){
		int opt, l, r, w;
		io >> opt >> l >> r;
		if(opt == 1){
			printf("%d\n", Query(l, r));
		}
		else{
			io >> w;
			Updata(l, r, w);
		}
	}

	return 0;
}
/*
13
9 4 12 18 19 1 11 18 16 5 1 10 9 2 1
3 1
4 1
5 1
6 4
7 3
8 3
9 3
10 8
11 9
12 10
13 10
5
2 1 10 10
2 7 13 6
1 5 9
1 4 10
1 9 10
*/