bzoj4568(合并线性基+倍增)

裸题练习模板

#include<iostream>
#include<cstring>
#include<cmath>
#include<cstdio>
#include<algorithm>
#include<vector> 
using namespace std;
typedef long long ll;
const int maxn=40010;
vector<ll>v[maxn][16];
int d[maxn],n,Q,fa[maxn][16],last[maxn],pre[maxn],other[maxn],t;
void add(int x,int y){++t;pre[t]=last[x];last[x]=t;other[t]=y;}
ll x,q[maxn];
vector<ll> uni(vector<ll> a,vector<ll> b){
    vector<ll>ans;
    int top=0,lena=a.size(),lenb=b.size();
    for(int i=0;i<lena;++i)q[++top]=a[i];
    for(int i=0;i<lenb;++i)q[++top]=b[i];
    int p=0;
    for(int j=60;j>=0;--j){
        bool flag=0;
        for(int i=p+1;i<=top;++i)
        if((q[i]>>j)&1){
            swap(q[i],q[++p]);
            flag=1;break;
        }
        if(!flag)continue;
        for(int i=1;i<=top;++i)
        if(i!=p){
            if((q[i]>>j)&1)q[i]^=q[p];
        }
    }
    for(int i=1;i<=p;++i)ans.push_back(q[i]);
    return ans;
}
void dfs(int x){
    for(int i=last[x];i;i=pre[i]){
        int v=other[i];
        if(v==fa[x][0])continue;
        d[v]=d[x]+1;fa[v][0]=x;
        dfs(v);
    }
}
int lca(int x,int y){
    if(d[x]<d[y])swap(x,y);
    for(int i=15;i>=0;--i)
    if(d[fa[x][i]]>=d[y])x=fa[x][i];
    if(x==y)return x;
    for(int i=15;i>=0;--i)
    if(fa[x][i]!=fa[y][i])x=fa[x][i],y=fa[y][i];
    return fa[x][0];
}
int jump(int x,int y){
    for(int i=15;i>=0;--i){
        if((1<<i)&y)x=fa[x][i];
    }
    return x;
}
vector<ll> qs(int x,int y){
    int k=log2(d[x]-d[y]+1);
    return uni(v[x][k],v[jump(x,d[x]-d[y]+1-(1<<k))][k]);
}
int main(){
    cin>>n>>Q;
    for(int i=1;i<=n;++i){
        scanf("%lld",&x);
        v[i][0].push_back(x);
    }
    int a,b,tmp;
    for(int i=1;i<n;++i){
        scanf("%d%d",&a,&b);
        add(a,b);add(b,a);
    }
    dfs(1);
    for(int j=1;j<=15;++j)
    for(int i=1;i<=n;++i){
        fa[i][j]=fa[fa[i][j-1]][j-1];
        v[i][j]=uni(v[i][j-1],v[fa[i][j-1]][j-1]);
    }
    while(Q--){
        scanf("%d%d",&a,&b);
        tmp=lca(a,b);
        vector<ll>ans=uni(qs(a,tmp),qs(b,tmp));
        ll res=0,siz=ans.size();
        for(int i=0;i<siz;++i)
        if((res^ans[i])>res)res^=ans[i];
        printf("%lld\n",res);
    }
    return 0;
}