题面
Sol
神题
给每个点对随机一个权值，把这两个点的权值异或上这个随机的值
用\(LCT\)维护子树信息，若子树异或和为所有点对的异或和那么就是答案
大常数代码
# include <bits/stdc++.h>
# define RG register
# define IL inline
# define Fill(a, b) memset(a, b, sizeof(a))
using namespace std;
typedef long long ll;
const int _(1e5 + 5);
IL int Input(){
RG int x = 0, z = 1; RG char c = getchar();
for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;
for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
return x * z;
}
int n, m, ch[_][2], fa[_], size[_], sum[_], val[_], rev[_], S[_], top, Sum;
struct Edge{
int u, v, w;
} P[_ << 2];
# define ls ch[x][0]
# define rs ch[x][1]
IL bool Son(RG int x){
return ch[fa[x]][1] == x;
}
IL bool Isroot(RG int x){
return ch[fa[x]][0] != x && ch[fa[x]][1] != x;
}
IL void Reverse(RG int x){
if(!x) return;
rev[x] ^= 1; swap(ls, rs);
}
IL void Pushdown(RG int x){
if(!rev[x]) return;
Reverse(ls); Reverse(rs); rev[x] = 0;
}
IL void Update(RG int x){
sum[x] = val[x] ^ size[x] ^ sum[ls] ^ sum[rs];
}
IL void Rotate(RG int x){
RG int y = fa[x], z = fa[y], c = Son(x);
if(!Isroot(y)) ch[z][Son(y)] = x; fa[x] = z;
ch[y][c] = ch[x][!c]; fa[ch[y][c]] = y;
ch[x][!c] = y; fa[y] = x;
Update(y);
}
IL void Splay(RG int x){
S[top = 1] = x;
for(RG int y = x; !Isroot(y); y = fa[y]) S[++top] = fa[y];
while(top) Pushdown(S[top--]);
for(RG int y = fa[x]; !Isroot(x); Rotate(x), y = fa[x])
if(!Isroot(y)) Son(x) ^ Son(y) ? Rotate(x) : Rotate(y);
Update(x);
}
IL void Access(RG int x){
for(RG int y = 0; x; y = x, x = fa[x]){
Splay(x);
size[x] ^= sum[rs] ^ sum[y];
rs = y; Update(x);
}
}
IL void Makeroot(RG int x){
Access(x); Splay(x); Reverse(x);
}
IL void Link(RG int x, RG int y){
Makeroot(x); Makeroot(y); fa[x] = y;
size[y] ^= sum[x]; Update(y);
}
IL void Split(RG int x, RG int y){
Makeroot(x); Access(y); Splay(y);
}
IL void Cut(RG int x, RG int y){
Split(x, y); fa[x] = ch[y][0] = 0;
}
# define yyb 141905
# define lrh 141936
# define ni_dong_de +
int main(RG int argc, RG char* argv[]){
srand(yyb ni_dong_de lrh);
Input(); n = Input(); m = Input();
for(RG int i = 1, x, y; i < n; ++i)
x = Input(), y = Input(), Link(x, y);
for(RG int i = 1, tot = 0; i <= m; ++i){
RG int opt = Input(), x = Input(), y, u, v;
if(opt == 1){
y = Input(), u = Input(), v = Input();
Cut(x, y), Link(u, v);
}
else if(opt == 2){
P[++tot].u = x, P[tot].v = y = Input();
P[tot].w = rand() % 19260817;
Makeroot(x); val[x] ^= P[tot].w; Update(x);
Makeroot(y); val[y] ^= P[tot].w; Update(y);
Sum ^= P[tot].w;
}
else if(opt == 3){
Makeroot(P[x].u); val[P[x].u] ^= P[x].w; Update(P[x].u);
Makeroot(P[x].v); val[P[x].v] ^= P[x].w; Update(P[x].v);
Sum ^= P[x].w;
}
else{
y = Input(); Split(x, y);
if(sum[x] ^ Sum) puts("NO");
else puts("YES");
}
}
return 0;
}