p4151 [WC2011]最大XOR和路径

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cctype>
#include<cmath>
#include<cstdlib>
#include<queue>
#include<ctime>
#include<vector>
#include<set>
#include<map>
#include<stack>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back 
#define li long long
vector<pair<int,li> >v[100100];
int n,m,vis[100100];
li bel[110],d[100100],ans;
inline void ins(li x){
    for(int i=63;i>=0;i--)
      if((1ll<<i)&x){
          if(!bel[i]){
            bel[i]=x;
            break;
          }
          x^=bel[i];
      }
}
inline void q(){
    for(int i=63;i>=0;i--)
      if((bel[i]^ans)>ans){
          ans^=bel[i];
      }
}
inline void dfs(int x,li res){
    d[x]=res;
    vis[x]=1;
    for(int i=0;i<v[x].size();i++){
      int y=v[x][i].fi;
      li z=v[x][i].se;
      if(!vis[y])dfs(y,res^z);
        else ins(res^z^d[y]);
    }
}
int main(){
    int i,j,k;
    scanf("%d%d",&n,&m);
    for(i=1;i<=m;i++){
      int x,y;
      li z;
      scanf("%d%d%lld",&x,&y,&z);
      v[x].pb(mp(y,z));
      v[y].pb(mp(x,z));
    }
    dfs(1,0ll);
    ans=d[n];
    q();
    printf("%lld\n",ans);
    return 0;
}