[BZOJ 2631]tree

裸LCT。。QAQ写了三遍没写对

真是老了。。QAQ

主要错的地方是

init:

size[i] = sum[i] = val[i] = mul[i] = 1;

pushdown:

注意判断左右儿子是否为空

splay:

前面有pushdown, stack..

while(!isroot(p)){

  int x = fa[p], y = fa[x];

  if(!isroot(x))...

}

Access:

while(u){

...

  c[u][1] = t;

  u = fa[u];
}

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define maxn 100010
using namespace std;

typedef long long ll;

const int md = 51061;

int n, q;
int c[maxn][2], fa[maxn], val[maxn], mul[maxn], add[maxn];
int sum[maxn], top, st[maxn], size[maxn];
bool rev[maxn];
namespace splay{
	inline void Mul(int& x, ll y){
		x = x * y % md;
	}
	inline void Add(int& x, ll y){
		x = (x + y) % md;
	}
	
	void init(){
		for(int i = 1; i <= n; i ++)
		    val[i] = mul[i] = 1, add[i] = 0;
	}
	
	inline void pushup(int x){
		sum[x] = (sum[c[x][0]] + sum[c[x][1]] + val[x]) % md;
		size[x] = size[c[x][0]] + size[c[x][1]] + 1;
	}
	
	inline void pushdown(int x){
		if(rev[x]){
			if(c[x][0])rev[c[x][0]] ^= 1;
			if(c[x][1])rev[c[x][1]] ^= 1;
			swap(c[x][0], c[x][1]);
			rev[x] = 0;
		}
		
		int lc = c[x][0], rc = c[x][1];
		if(lc != 0){
			if(mul[x] != 1){
				Mul(mul[lc], mul[x]);
				Mul(add[lc], mul[x]);
				Mul(val[lc], mul[x]);
				Mul(sum[lc], mul[x]);
			}
			if(add[x] != 0){
				Add(add[lc], add[x]);
				Add(val[lc], add[x]);
				Add(sum[lc], (ll)size[lc] * add[x]);
			}
		}
		
		if(rc != 0){
            if(mul[x] != 1){
				Mul(mul[rc], mul[x]);
				Mul(add[rc], mul[x]);
				Mul(val[rc], mul[x]);
				Mul(sum[rc], mul[x]);
			}
			if(add[x] != 0){
				Add(add[rc], add[x]);
				Add(val[rc], add[x]);
				Add(sum[rc], (ll)size[rc] * add[x]);
			}
		}
		mul[x] = 1, add[x] = 0;
	}

	inline bool isroot(int x){
		return c[fa[x]][0] != x && c[fa[x]][1] != x;
	}
	
	inline void rotate(int p, int x){
		int mark = p == c[x][1], y = c[p][mark^1], z = fa[x];
		if(c[z][0] == x) c[z][0] = p;
		if(c[z][1] == x) c[z][1] = p;
		if(y) fa[y] = x;
		c[p][mark^1] = x, fa[p] = z;
		c[x][mark] = y, fa[x] = p;
		pushup(x);
	}
	
	inline void splay(int p){
		st[top = 1] = p;
		for(int i = p; !isroot(i); i = fa[i])
		    st[++ top] = fa[i];
		while(top) pushdown(st[top --]);
		while(!isroot(p)){
			int x = fa[p], y = fa[x];
			if(isroot(x))rotate(p, x);
			else if(p == c[x][0] ^ x == c[y][0])
				rotate(p, x), rotate(p, y);
			else rotate(x, y), rotate(p, x);
		}
		pushup(p);
	}
	
	inline void update(int x, int mu, int ad){
		if(mu != 1){
			Mul(val[x], mu);
			Mul(mul[x], mu);
			Mul(add[x], mu);
			Mul(sum[x], mu);
		}
		
		if(ad != 0){
			Add(val[x], ad);
			Add(add[x], ad);
			Add(sum[x], (ll)size[x] * ad);
		}
	}
}


namespace LCT{
	void Access(int u){
		int t = 0;
		while(u){
			splay::splay(u);
			c[u][1] = t;
			t = u;
			splay::pushup(u);
			u = fa[u];
		}
	}
	
	void Evert(int u){
		Access(u);
		splay::splay(u);
		rev[u] ^= 1;
		splay::pushdown(u);
	}
	
	void link(int u, int v){
		Evert(u);
		fa[u] = v;
		//Access(u); splay::splay(u);
	}
	
	void cut(int u, int v){
		Evert(u);
		Access(v);
		splay::splay(v);
		c[v][0] = fa[u] = 0;
		splay::pushup(v);
	}
	
	void update(int u, int v, int mu, int ad){
		Evert(u), Access(v);
		splay::splay(v);
        splay::update(v, mu, ad);
	}
	
	int ask(int u, int v){
        Evert(u), Access(v);
        splay::splay(v);
        return sum[v];
	}
}

int main(){
	scanf("%d%d", &n, &q);
	splay::init();
	int u, v, u1, v1, c;
	for(int i = 1; i < n; i ++){
		scanf("%d%d", &u, &v);
		LCT::link(u, v);
	}
	for(int i = 1; i <= q; i ++){
		char ch = getchar();
		for(; ch < '!'; ch = getchar());
		if(ch == '+'){
			scanf("%d%d%d", &u, &v, &c);
			LCT::update(u, v, 1, c);
		}
		if(ch == '-'){
			scanf("%d%d%d%d", &u, &v, &u1, &v1);
			LCT::cut(u, v);
			LCT::link(u1, v1);
		}
		if(ch == '*'){
            scanf("%d%d%d", &u, &v, &c);
			LCT::update(u, v, c, 0);
		}
		if(ch == '/'){
			scanf("%d%d", &u, &v);
			printf("%d
", LCT::ask(u, v));
		}
	}
	return 0;
}