[SCOI2016]幸运数字

Posted 2022-03-23 mle-world

算简单的了，直接拿线性基维护路径异或然后倍增跳合并就行。

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<queue>
#include<set>
#include<map>
#include<iostream>
using namespace std;
#define re register
#define ll long long
inline int gi()
    int f=1,sum=0;char ch=getchar();
    while(ch>'9' || ch<'0')if(ch=='-')f=-1;ch=getchar();
    while(ch>='0' && ch<='9')sum=(sum<<3)+(sum<<1)+ch-'0';ch=getchar();
    return f*sum;

inline ll gl()
    ll f=1,sum=0;char ch=getchar();
    while(ch>'9' || ch<'0')if(ch=='-')f=-1;ch=getchar();
    while(ch>='0' && ch<='9')sum=(sum<<3)+(sum<<1)+ch-'0';ch=getchar();
    return f*sum;

const int N=20010;
struct xxj
    ll p[62];
    void insert(ll &x)
        for(int i=61;~i;i--)
            if((x>>i)&1)
                if(!p[i])p[i]=x;return;
                x^=p[i];
            
        return;
    
    void merge(xxj &b)
        for(int i=61;~i;i--)
            if(b.p[i])insert(b.p[i]);
        return;
    
xj[N][17],ans;//15
int f[N][17],n,Q,front[N],cnt;
struct nodeint to,nxt;e[400010];
void Add(int u,int v)e[++cnt]=(node)v,front[u];front[u]=cnt;
ll g[N];
int dep[N];
void dfs(int u,int ff)
    f[u][0]=ff;xj[u][0].insert(g[u]);dep[u]=dep[ff]+1;
    for(int i=front[u];i;i=e[i].nxt)
        int v=e[i].to;if(v==ff)continue;
        dfs(v,u);
    

void lca(int u,int v)
    if(dep[u]<dep[v])swap(u,v);
    memset(ans.p,0,sizeof(ans.p));
    for(int i=15;~i;i--)
        if(dep[u]-(1<<i)>=dep[v])
            ans.merge(xj[u][i]);
            u=f[u][i];
        
    if(u==v)
        ans.merge(xj[u][0]);
        return;
    
    for(int i=15;~i;i--)
        if(f[u][i]!=f[v][i])
            ans.merge(xj[u][i]);ans.merge(xj[v][i]);
            u=f[u][i],v=f[v][i];
        
    ans.merge(xj[u][0]);ans.merge(xj[v][0]);
    ans.merge(xj[f[u][0]][0]);

int main()
    n=gi();Q=gi();
    for(int i=1;i<=n;i++)g[i]=gl();
    for(int i=1;i<n;i++)int u=gi(),v=gi();Add(u,v);Add(v,u);
    dfs(1,1);
    for(int j=1;j<=15;j++)
        for(int i=1;i<=n;i++)
            f[i][j]=f[f[i][j-1]][j-1];
            xj[i][j]=xj[i][j-1];
            xj[i][j].merge(xj[f[i][j-1]][j-1]);
        
    while(Q--)
        int u=gi(),v=gi();
        lca(u,v);
        ll sum=0;
        for(int i=61;~i;i--)
            if(ans.p[i])sum=max(sum,sum^(ll)ans.p[i]);
        printf("%lld\n",sum);
    
    return 0;