spoj Query on a tree again（树链剖分）

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
const int MAXN=100004;
int n,m;
int head[MAXN],edge=0;
int siz[MAXN],son[MAXN],fa[MAXN],top[MAXN],tid[MAXN],rk[MAXN],dep[MAXN],tim=0;
struct EDGE {
int v,nxt;
}e[MAXN<<1];
inline int read() {
int x=0;char c=getchar();
while (c<'0'||c>'9') c=getchar();
while (c>='0'&&c<='9') x=x*10+c-'0',c=getchar();
return x;
}
inline void adde(int u,int v) {
e[++edge].nxt=head[u],e[edge].v=v,head[u]=edge;
e[++edge].nxt=head[v],e[edge].v=u,head[v]=edge;
}
/*------------DCP------------*/
void dfs1(int p,int father,int d) {
siz[p]=1,fa[p]=father,dep[p]=d;
for (int i=head[p];~i;i=e[i].nxt) {
int v=e[i].v;
if (v^father) {
dfs1(v,p,d+1);
siz[p]+=siz[v];
if (son[p]==-1||siz[son[p]]<siz[v]) son[p]=v;
}
}
}
void dfs2(int p,int tp) {
top[p]=tp,tid[p]=++tim,rk[tim]=p;
if (son[p]==-1) return ;
dfs2(son[p],tp);
for (int i=head[p];~i;i=e[i].nxt) {
int v=e[i].v;
if (v^fa[p]&&v^son[p])
dfs2(v,v);
}
}
/*------------SegTree------------*/
int sum[MAXN<<2];
inline void pushup(int rt) {
sum[rt]=sum[rt<<1]+sum[rt<<1|1];
}
void modify(int rt,int l,int r,int pos,int val) {
if (l==r) {sum[rt]^=val;return ;}
int mid=(l+r)>>1;
if (pos<=mid) modify(rt<<1,l,mid,pos,val);
else modify(rt<<1|1,mid+1,r,pos,val);
pushup(rt);
}
int query(int rt,int l,int r,int L,int R) {
if (!sum[rt]) return 0;
if (l==r) return l;
int mid=(l+r)>>1;
int ans=0;
if (L<=mid) ans=query(rt<<1,l,mid,L,R);
if (ans) return ans;
if (mid<R) ans=query(rt<<1|1,mid+1,r,L,R);
return ans;
}
int ask(int x,int y) {
int ans=0;
while (top[x]^top[y]) {
if (dep[top[x]]<dep[top[y]]) x^=y^=x^=y;
int temp=query(1,1,n,tid[top[x]],tid[x]);
if (temp) ans=temp;
x=fa[top[x]];
}
if (dep[x]>dep[y]) x^=y^=x^=y;
int temp=query(1,1,n,tid[x],tid[y]);
if (temp) ans=temp;
return ans;
}
int main() {
//  freopen("spoj qota.in","r",stdin);
memset(head,-1,sizeof(head));
memset(son,-1,sizeof(son));
n=read(),m=read();
for (register int i=1;i<n;++i) {
int u=read(),v=read();
adde(u,v);
}
dfs1(1,0,0);
dfs2(1,1);
for (register int C_Ronaldo=0;C_Ronaldo<m;++C_Ronaldo) {
int x=read(),y=read();
if (!x) modify(1,1,n,tid[y],1);
else {
int ret=ask(1,y);
printf("%d\n",ret?rk[ret]:-1);
}
}
return 0;
}