Submission #66732193

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Source Code Expand

#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

bool visited[1000][1 << 10];

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<vector<P>> to(n);
  rep(_, m) {
    int a, b, w;
    cin >> a >> b >> w;
    a--, b--;
    to[a].emplace_back(b, w);
  }
  vector<P> todo;
  visited[0][0] = true;
  todo.emplace_back(0, 0);
  while (todo.size()) {
    auto [u, b] = todo.back(); todo.pop_back();
    for (auto [v, w] : to[u]) {
      int nb = b ^ w;
      if (!visited[v][nb]) {
        visited[v][nb] = true;
        todo.emplace_back(v, nb);
      }
    }
  }
  int ans = -1;
  rep(b, 1 << 10) if (visited[n-1][b]) {
    ans = b;
    break;
  }
  cout << ans << '\n';
}

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