#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 3e5 + 5;

struct Trie {
  int ch[N << 4][2], tot, id[N << 4];
  void init () {
    for (int i = 1; i <= tot; i ++) id[i] = ch[i][0] = ch[i][1] = 0;
    tot = 1;
  }
  void insert (int x, int ID) {
    int p = 1;
    for (int i = 32; i >= 0; i --) {
      int j = (x >> i) & 1;
      if (ch[p][j] == 0) ch[p][j] = ++ tot;
      p = ch[p][j];
    }
    id[p] = ID;
  }

  int ask_val (int x) {
    int p = 1, ans = 0;
    for (int i = 32; i >= 0; i --) {
      int j = ((x >> i) & 1) ^ 1;
      if (ch[p][j] == 0) j ^= 1;
      if (ch[p][j] == 0) return 0;
      ans |= (j << i); p = ch[p][j]; 
    }
    return ans;
  }

  int ask_ID (int x) {
    int p = 1;
    for (int i = 32; i >= 0; i --) {
      int j = ((x >> i) & 1) ^ 1;
      if (ch[p][j] == 0) j ^= 1;
      p = ch[p][j]; 
    }
    return id[p];
  }
} A, B;

int Xor[N], head[N], number, f[N], dfn[N], V[N], siz[N], gg, L[N], R[N], out[N], in[N];
bool vis[N];

struct node {
  int w, next, to; 
} g[N];

void add (int x, int y, int z) { g[++ number] = {z, head[x], y}; head[x] = number; }

void dfs (int x, int fa) {
  f[x] = fa; siz[x] = 1; dfn[x] = ++ gg; V[gg] = x;
  for (int i = head[x]; i; i = g[i].next) {
    int to = g[i].to, w = g[i].w;
    if (to == fa) continue;
    Xor[to] = Xor[x] ^ w;
    dfs (to, x); siz[x] += siz[to];
  }
  L[x] = dfn[x], R[x] = dfn[x] + siz[x] - 1;
}

stack <int> s;
int nxt[N];
void Get_Mark (int x) {
  B.init (); int ans = 0;
  while (x != 0) {
    B.insert (Xor[x], x); ans = max (ans, Xor[x] ^ B.ask_val (Xor[x]));
    for (int i = head[x]; i; i = g[i].next) {
      int to = g[i].to;
      if (to == f[x] or to == nxt[x]) continue;
      for (int j = L[to]; j <= R[to]; j ++) {
        int id = V[j];
        B.insert (Xor[id], id), ans = max (ans, Xor[id] ^ B.ask_val (Xor[id]));
      }
    }
    in[x] = ans;
    vis[x] = true;
    s.emplace (x);
    nxt[f[x]] = x;
    x = f[x]; 
  }
  ans = 0; B.init ();
  while (!s.empty ()) {
    int a = s.top (); s.pop ();
    out[a] = ans;
    B.insert (Xor[a], a); ans = max (ans, Xor[a] ^ B.ask_val (Xor[a]));
    for (int i = head[a]; i; i = g[i].next) {
      int to = g[i].to;
      if (to == f[a] or to == nxt[a]) continue;
      for (int j = L[to]; j <= R[to]; j ++) {
        B.insert (Xor[V[j]], V[j]);
        ans = max (ans, Xor[V[j]] ^ B.ask_val (Xor[V[j]]));
      }
    }
  }
}

void doit (int x) {
  B.init (); int ans = 0;
  for (int i = L[x]; i <= R[x]; i ++) {
    int j = V[i];
    B.insert (Xor[j], j); ans = max (ans, Xor[j] ^ B.ask_val (Xor[j])); 
  }
  in[x] = ans;
}
void dfs2 (int x) {
  for (int i = head[x]; i; i = g[i].next) {
    int to = g[i].to;
    if (to == f[x]) continue;
    if (vis[to] == false) doit (to);
    else dfs2 (to);
  }
}


signed main () {
  //freopen ("in.in", "r", stdin);
 // freopen ("out.out", "w", stdout);
  int n; cin >> n;
  for (int i = 1; i < n; i ++) {
    int x, y, z; cin >> x >> y >> z;
    add (x, y, z); add (y, x, z); 
  }
  dfs (1, 0); A.init ();
  for (int i = 1; i <= n; i ++)
    A.insert (Xor[i], i);
  int X, Y, Mx = -1e9;
  for (int i = 1; i <= n; i ++) {
    int j = A.ask_ID (Xor[i]);
    if (Xor[i] ^ Xor[j] > Mx) X = i, Y = j, Mx = Xor[i] ^ Xor[j];
  }
  Get_Mark (X), Get_Mark (Y); dfs2 (1);
  int ans = 0;
  for (int i = 1; i <= n; i ++) {
    if (vis[i] == false) ans = max (ans, in[i] + Mx);
    else ans = max (ans, in[i] + out[i]);
  }
  cout << ans << "\n";
}

每个subtask都错了一点