Submission #66757143

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#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define YES cout<<"Yes"<<endl
#define NO cout<<"No"<<endl
using ll=long long;
using pi=pair<int,int>;
const int di[]={+1,-1,+0,+0};
const int dj[]={+0,+0,+1,-1};
const int INF=1e9;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    vector<vector<pi>> G(n);
    rep(i, m) {
        int a, b, w;
        cin >> a >> b >> w;
 
 
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#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define YES cout<<"Yes"<<endl
#define NO cout<<"No"<<endl
using ll=long long;
using pi=pair<int,int>;
const int di[]={+1,-1,+0,+0};
const int dj[]={+0,+0,+1,-1};
const int INF=1e9;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    vector<vector<pi>> G(n);
    rep(i, m) {
        int a, b, w;
        cin >> a >> b >> w;
        a--; b--;
        G[a].push_back({w, b});
    }
    queue<int> que;
    que.push(0);
    vector<int> dist(n, -1);
    dist[0]=0;
    vector<int> basis(11);
    auto inbit=[&](ll x) {
        for(int bit=10; bit>=0; bit--) {
            if(!(x&(1LL<<bit))) continue;
            if(basis[bit]==0) {
                basis[bit]=x;
                break;
            }
            x^=basis[bit];
        }
    };
    while(!que.empty()) {
        int v=que.front();
        que.pop();
        for(auto [nw, nv]:G[v]) {
            if(dist[nv]==-1) {
                dist[nv]=dist[v]^nw;
                que.push(nv);
            } else {
                int cycle=dist[v]^nw^dist[nv];
                if(cycle) inbit(cycle);
            }
        }
    }
    if(dist.back()==-1) {
        cout << -1 << endl;
        return 0;
    }
    int ans=dist.back();
    for(int b=10; b>=0; b--) {
        if((ans^basis[b])<ans) ans^=basis[b];
    }
    cout << ans << endl;

    return 0;
}

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