2115. [Wc2011] Xor

https://hydro.ac/d/bzoj/record/6322efd8bdf9bc31d160a3c0

BZOJ/2115/2115.cpp

@@ -0,0 +1,69 @@
+#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].emplace_back(t, d);
+        g[t].emplace_back(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;
+}