Link Cut Tree
刚开始写了个指针版。。调了一天然后放弃了。。
最后还是学了黄学长的板子！！
#include <bits/stdc++.h>
#define INF 0x3f3f3f3f
#define full(a, b) memset(a, b, sizeof a)
using namespace std;
typedef long long ll;
inline int lowbit(int x){ return x & (-x); }
inline int read(){
int X = 0, w = 0; char ch = 0;
while(!isdigit(ch)) { w |= ch == '-'; ch = getchar(); }
while(isdigit(ch)) X = (X << 3) + (X << 1) + (ch ^ 48), ch = getchar();
return w ? -X : X;
}
inline int gcd(int a, int b){ return a % b ? gcd(b, a % b) : b; }
inline int lcm(int a, int b){ return a / gcd(a, b) * b; }
template<typename T>
inline T max(T x, T y, T z){ return max(max(x, y), z); }
template<typename T>
inline T min(T x, T y, T z){ return min(min(x, y), z); }
template<typename A, typename B, typename C>
inline A fpow(A x, B p, C lyd){
A ans = 1;
for(; p; p >>= 1, x = 1LL * x * x % lyd)if(p & 1)ans = 1LL * x * ans % lyd;
return ans;
}
const int N = 300005;
int ch[N][2], val[N], sum[N], rev[N], tot, fa[N], st[N], n, m;
void newNode(int v){
val[++tot] = v, sum[tot] = v;
rev[tot] = ch[tot][0] = ch[tot][1] = fa[tot] = 0;
}
void reverse(int x){
swap(ch[x][0], ch[x][1]);
rev[x] ^= 1;
}
void push_up(int x){
sum[x] = val[x] ^ sum[ch[x][0]] ^ sum[ch[x][1]];
}
void push_down(int x){
if(rev[x]){
reverse(ch[x][0]), reverse(ch[x][1]);
//rev[x] ^= 1, rev[ch[x][0]] ^= 1, rev[ch[x][1]] ^= 1;
//swap(ch[x][0], ch[x][1]);
rev[x] ^= 1;
}
}
bool isRoot(int x){
return (!fa[x] || (ch[fa[x]][0] != x && ch[fa[x]][1] != x));
}
void rotate(int x){
int y = fa[x], z = fa[y], p = (ch[y][1] == x)^1;
ch[y][p^1] = ch[x][p], fa[ch[x][p]] = y;
if(!isRoot(y)) ch[z][ch[z][1] == y] = x;
fa[x] = z, ch[x][p] = y, fa[y] = x;
push_up(y), push_up(x);
}
void splay(int x){
int pos = 0; st[++pos] = x;
for(int i = x; !isRoot(i); i = fa[i]) st[++pos] = fa[i];
while(pos) push_down(st[pos --]);
while(!isRoot(x)){
int y = fa[x], z = fa[y];
if(!isRoot(y)){
if((ch[y][1] == x) ^ (ch[z][1] == y)) rotate(x);
else rotate(y);
}
rotate(x);
}
}
void access(int x){
for(int p = 0; x; p = x, x = fa[x])
splay(x), ch[x][1] = p, push_up(x);
}
void makeRoot(int x){
access(x), splay(x), reverse(x);
}
int findRoot(int x){
access(x), splay(x);
while(ch[x][0]) push_down(x), x = ch[x][0];
splay(x);
return x;
}
void split(int x, int y){
makeRoot(x), access(y), splay(y);
}
void link(int x, int y){
makeRoot(x);
if(findRoot(y) == x) return;
fa[x] = y;
push_up(y);
}
void cut(int x, int y){
makeRoot(x);
if(findRoot(y) != x || fa[y] != x || ch[y][0]) return;
ch[x][1] = fa[y] = 0;
push_up(x);
}
int main(){
n = read(), m = read();
for(int i = 1; i <= n; i ++){
int v = read(); newNode(v);
}
while(m --){
int opt = read(), x = read(), y = read();
if(opt == 0){
split(x, y); printf("%d\n", sum[y]);
}
else if(opt == 1){
link(x, y);
}
else if(opt == 2){
cut(x, y);
}
else if(opt == 3){
splay(x); val[x] = y;
}
}
return 0;
}