arbori_xor

#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
using namespace std;
ifstream fin("arbori_xor.in");
ofstream fout("arbori_xor.out");
deque <int> coada;
vector <pair<int,int> > L[10009];
int s[10009],t[10009],n,q,i,x,y,z,a,b;
void bfs(int nod){
    int vecin;
    int cost;
    coada.push_back(nod);
while(!coada.empty()){
    nod=coada.front();
    coada.pop_front();
for(int i=0;i<L[nod].size();i++){
        vecin=L[nod][i].first;
        cost=L[nod][i].second;
    if(t[nod]==vecin)
        continue;
    coada.push_back(vecin);
    t[vecin]=nod;
    s[vecin]=s[nod]^cost;
}
}
}
int query(int a,int b){
    return s[a]^s[b];
}
int main()
{
    fin>>n>>q;
    for(i=1;i<n;i++){
        fin>>x>>y>>z;
        L[x].push_back({y,z});
        L[y].push_back({x,z});
    }
    bfs(1);
    for(i=1;i<=q;i++){
        fin>>a>>b;
        fout<<query(a,b)<<"\n";
    }
}