0
1
mirror of https://git.sb/baoshuo/OI-codes.git synced 2024-12-25 16:11:58 +00:00
OI-codes/Luogu/P4151/P4151.cpp

70 lines
1.2 KiB
C++

#include <iostream>
#include <utility>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 50005;
int n, m;
bool vis[N];
unsigned long long p[N], dep[N], ans;
std::vector<std::pair<int, unsigned long long>> g[N];
inline void insert(unsigned long long x) {
for (int i = 60; ~i; i--) {
if (x & (1ull << i)) {
if (p[i]) {
x ^= p[i];
} else {
p[i] = x;
return;
}
}
}
}
void dfs(int u, unsigned long long sum) {
vis[u] = true;
dep[u] = sum;
for (auto e : g[u]) {
int v = e.first;
unsigned long long w = e.second;
if (vis[v]) insert(sum ^ dep[v] ^ w);
else dfs(v, sum ^ w);
}
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
for (int i = 1; i <= m; i++) {
int s, t;
unsigned long long d;
cin >> s >> t >> d;
g[s].push_back(std::make_pair(t, d));
g[t].push_back(std::make_pair(s, d));
}
dfs(1, 0);
ans = dep[n];
for (int i = 60; ~i; i--) {
if ((ans ^ p[i]) > ans) ans ^= p[i];
}
cout << ans << endl;
return 0;
}