代码如下

#include<bits/stdc++.h>
using namespace std;
const int MAXN = 5e5 + 10;
struct Edge{
	int to;
	int next;
	int weight;
}edge[MAXN << 1];
int head[MAXN << 1],cnt = 0,d[MAXN << 1];
int n;

void init(){
	for(int i = 0;i < MAXN * 2;i++){
		edge[i].next = -1;
		head[i] = -1;
		edge[i].weight = 0;
		d[i] = 0;
	}
	cnt = 0;
}
void addedge(int u,int v,int w){
	edge[cnt].to = v;
	edge[cnt].weight = w;
	edge[cnt].next = head[u];
	head[u] = cnt++;
}

void dfs(int x,int father){
	for(int i = head[x];i != -1;i = edge[i].next){
		if(edge[i].to != father){
			if(x != 1){
				d[edge[i].to] = d[x] ^ edge[i].weight;
			}else{
				d[edge[i].to] = edge[i].weight;
			}
			dfs(edge[i].to,x);
		}
	}
}

int trie[MAXN << 2][2],cntt = 1;
void insert(int a){
	int p = 1;
	for(int i = 30;i >= 0;i--){
		int ch = ((a >> i) & 1);
		if(trie[p][ch] != 0){
			trie[p][ch] = ++cntt; 
		}
		p = trie[p][ch];
	}
}
int find(int a){
	int p = 1,ans = 0;
	for(int i = 30;i >= 0;i--)
    {
        int ch = !((a >> i) & 1);
        if(trie[p][ch] != 0){
            if(trie[p][!ch]) p = trie[p][!ch];
            else return ans;
        }else p = trie[p][ch], ans += (1 << i);
    }
    return ans;
}

int main(){
	cin >> n;
	init();
	for(int i = 1;i < n;i++){
		int u,v,w;
		cin >> u >> v >> w;
		addedge(u,v,w);
		addedge(v,u,w);
	}
	dfs(1,0);
	for(int i = 1;i <= n;i++){
		insert(d[i]);
	}
	int ans = 0;
	for(int i=1;i<=n;++i){
        int t = find(d[i]);
        if(t>ans) ans=t;
    }
	cout << ans;
	return 0;
}

字典树部分是照着题解写的，但是输出结果总是2147483647。。