總結
一般最大異或題,都是轉換成枚舉n在trie上跑,也就是nlogn,n=1e5
題目鏈接
//#pragma GCC optimize(2)
#include<bits/stdc++.h>
//typedef long long ll;
#define ull unsigned long long
#define int long long
#define F first
#define S second
#define endl "\n"//<<flush
#define eps 1e-6
#define base 131
#define lowbit(x) (x&(-x))
#define PI acos(-1.0)
#define inf 0x3f3f3f3f
#define MAXN 0x7fffffff
#define INF 0x3f3f3f3f3f3f3f3f
#define ferma(a,b) pow(a,b-2)
#define pb push_back
#define all(x) x.begin(),x.end()
#define memset(a,b) memset(a,b,sizeof(a));
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
using namespace std;
void file()
{
#ifdef ONLINE_JUDGE
#else
freopen("D:/LSNU/codeforces/duipai/data.txt","r",stdin);
// freopen("D:/LSNU/codeforces/duipai/WA.txt","w",stdout);
#endif
}
const int N=1e5+5;
int son[N*32][2],dp[N],pos=0;
vector<pair<int,int> >G[N];
void dfs(int u,int fat)
{
for(auto it:G[u])
{
int v=it.F;
if(v==fat)
continue;
dp[v]=dp[u]^it.S;
dfs(v,u);
}
}
void insert(int num)
{
int p=0;
for(int i=30;i>=0;i--)
{
int &t=son[p][num>>i&1];
if(!t)
t=++pos;
p=t;
}
}
int query(int num)
{
int sum=0,p=0;
for(int i=30;i>=0;i--)
{
if(son[p][num>>i&1^1])
sum+=1<<i,p=son[p][num>>i&1^1];
else
p=son[p][num>>i&1];
}
return sum;
}
signed main()
{
IOS;
// file();
int n;
cin>>n;
for(int i=1;i<n;i++)
{
int u,v,dis;
cin>>u>>v>>dis;
G[u].pb({v,dis});
G[v].pb({u,dis});
}
dfs(0,-1);
for(int i=0;i<n;i++)
insert(dp[i]);
int ans=0;
for(int i=0;i<n;i++)
ans=max(ans,query(dp[i]));
cout<<ans<<endl;
return 0;
}