[WC2011]最大XOR和路径

#include<bits/stdc++.h>
#define il inline
#define reg register int
#define numb (ch^‘0‘)
using namespace std;
typedef long long ll;
il void rd(int &x){
    char ch;bool fl=false;
    while(!isdigit(ch=getchar()))(ch==‘-‘)&&(fl=true);
    for(x=numb;isdigit(ch=getchar());x=x*10+numb);
    (fl==true)&&(x=-x);
}
namespace Miracle{
const int N=50000+5;
const int M=100000+5;
struct node{
    int nxt,to;
    ll val;
}e[2*M];
int hd[N],cnt=1;
int n,m;
void add(int x,int y,ll z){
    e[++cnt].nxt=hd[x];
    e[cnt].to=y;
    e[cnt].val=z;
    hd[x]=cnt;
}
struct linebase{
    ll a[70];
    void ins(ll x){
        for(reg i=61;i>=0;--i){
            if(x&((ll)1<<i)){
                if(!a[i]){
                    a[i]=x;return;
                }
                else{
                    x^=a[i];
                }
            }
        }
        return;
    }    
    ll query(ll x){
        ll ret=x;
        for(reg i=61;i>=0;--i){
            if(a[i]){
                if((ret^a[i])>ret) ret^=a[i];
            }
        }
        return ret;
    }
}lb;
ll f[N];
bool vis[N];
void dfs(int x,int in_edge){
    vis[x]=1;
    for(reg i=hd[x];i;i=e[i].nxt){
        int y=e[i].to;
        if(i==(in_edge^1)) continue;
        if(!vis[y]){
            f[y]=f[x]^e[i].val;
            dfs(y,i);
        }else{
            ll tmp=f[x]^f[y]^e[i].val;
            lb.ins(tmp);
        }
    }
}
int main(){
    rd(n);rd(m);
    int x,y;
    ll z;
    for(reg i=1;i<=m;++i){
        rd(x);rd(y);scanf("%lld",&z);
        add(x,y,z);add(y,x,z);
    }
    dfs(1,0);
    printf("%lld\n",lb.query(f[n]));
    return 0;
}

}
signed main(){
    Miracle::main();
    return 0;
}

/*
   Author: *Miracle*
   Date: 2019/1/1 16:08:00
*/