P5283 [十二省联考2019]异或粽子 可持久化字典树

#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define repp(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
#define see(x) (cerr<<(#x)<<‘=‘<<(x)<<endl)
#define inf 0x3f3f3f3f
#define CLR(A,v)  memset(A,v,sizeof A)
//////////////////////////////////
const int N=2e6+10;
int T[N],t[N<<5][2],ncnt,siz[N<<5];
void upnode(int k,ll val,int v,int pre,int &pos)
{
    pos=++ncnt;
    t[pos][0]=t[pre][0];
    t[pos][1]=t[pre][1];
    siz[pos]=siz[pre]+v;
    if(k==-1)return ;
    if( (val>>k)&1 )upnode(k-1,val,v,t[pre][1],t[pos][1]);
    else upnode(k-1,val,v,t[pre][0],t[pos][0]);
}
ll qmax(int k,ll val,int pos)
{
    if(k==-1)return 0;
    int c=(val>>k)&1;
    if(siz[t[pos][c^1]])return qmax(k-1,val,t[pos][c^1])+(1<<k);
    else return qmax(k-1,val,t[pos][c]);
}
struct node{ll v;int x;};
bool operator< (node a,node b){return a.v<b.v;}
priority_queue<node>q;
ll a[N],ans;int n,k;
int main()
{
    scanf("%d%d",&n,&k);
    rep(i,1,n)
    {
        ll x;scanf("%lld",&x);a[i]=a[i-1]^x;
    }
    //upnode(32,0,1,T[0],T[0]);
    rep(i,1,n)upnode(32,a[i-1],1,T[i-1],T[i]);
    
    rep(i,1,n)q.push((node){qmax(32,a[i],T[i]),i});
    while(k--)
    {
        node u=q.top();q.pop();
        ans+=u.v;
        upnode(32,u.v^a[u.x],-1,T[u.x],T[u.x]);
        q.push((node){qmax(32,a[u.x],T[u.x]),u.x});
    }
    cout<<ans;

    return 0;
}