Luogu P4551 最长异或路径 01trie

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<cctype>
#include<cstdlib>
#include<vector>
#include<queue>
#include<map>
#include<set>
#define ll long long
#define R register int
using namespace std;
namespace Fread {
    static char B[1<<15],*S=B,*D=B;
    #define getchar() (S==D&&(D=(S=B)+fread(B,1,1<<15,stdin),S==D)?EOF:*S++)
    inline int g() {
        R ret=0,fix=1; register char ch; while(!isdigit(ch=getchar())) fix=ch==‘-‘?-1:fix;
        do ret=ret*10+(ch^48); while(isdigit(ch=getchar())); return ret*fix;
    }
}using Fread::g;
const int N=100010;
int cnt,n,m,tot;
int vr[N<<1],nxt[N<<1],w[N<<1],fir[N],d[N];
int t[N*32][2];
inline void add(int u,int v,int ww) {vr[++cnt]=v,w[cnt]=ww,nxt[cnt]=fir[u],fir[u]=cnt;}
inline void dfs(int u,int fa) {
    for(R i=fir[u];i;i=nxt[i]) { R v=vr[i];
        if(v==fa) continue; d[v]=d[u]^w[i]; dfs(v,u);
    }
}
inline void ins(int x) { R now=0;
    for(R i=30;~i;--i) {
        R ch=(x>>i)&1; if(!t[now][ch]) t[now][ch]=++tot;
        now=t[now][ch];
    }
}
inline int query(int x) { R now=0,ret=0;
    for(R i=30;~i;--i) {
        R ch=(x>>i)&1; if(!t[now][!ch]) now=t[now][ch];
        else now=t[now][!ch],ret+=(1<<i);
    } return ret;
}
signed main() {
#ifdef JACK
    freopen("NOIPAK++.in","r",stdin);
#endif
    n=g();
    for(R i=1,u,v,w;i<n;++i) u=g(),v=g(),w=g(),add(u,v,w),add(v,u,w);
    dfs(1,0); for(R i=1;i<=n;++i) ins(d[i]); R ans=0;
    for(R i=1;i<=n;++i) ans=max(ans,query(d[i])); printf("%d\n",ans);     
}