洛谷 [P2420] 让我们异或吧

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
using namespace std;
int read(){
int rv=0,fh=1;
char c=getchar();
while(c<'0'||c>'9'){
if(c=='-') fh=-1;
c=getchar();
}
while(c>='0'&&c<='9'){
rv=(rv<<1)+(rv<<3)+c-'0';
c=getchar();
}
return rv*fh;
}
const int MAXN=100005;
int n,m,po[MAXN],dis[MAXN],nume,numq;
bool f[MAXN];
struct edge{
int to,nxt,dis;
}e[MAXN*2];
void adde(int from,int to,int dis){
e[++nume].to=to;
e[nume].nxt=po[from];
e[nume].dis=dis;
po[from]=nume;
}
void dfs(int u,int val){
f[u]=1;
dis[u]=val;
for(int i=po[u];i;i=e[i].nxt){
int v=e[i].to;
if(!f[v]){
dfs(v,val^e[i].dis);
}
}
}
int main(){
freopen("in.txt","r",stdin);
n=read();
for(int i=1;i<n;i++){
int u=read(),v=read(),dis=read();
adde(u,v,dis);adde(v,u,dis);
}
m=read();
dfs(1,0);
for(int i=1;i<=m;i++){
int u=read(),v=read();
//addq(u,v,num);addq(u,v,num);
printf("%d\n",dis[u]^dis[v]);
}
fclose(stdin);
return 0;
}