记得关注
```cpp
#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
const int N=20000000+10;
struct Node{int id,rk;long long w;bool operator <(const Node &a)const{return w<a.w;}};
priority_queue<Node>q;
long long ans=1,x,s[N];
int a[N][2],size[N],n,m,tot;
void ins(long long x)
{
int u=0;
for(int i=31;i>=0;i--)
{
int ch=(x>>i)&1;size[u]++;
if(!a[u][ch])a[u][ch]=++tot;
u=a[u][ch];
}
size[u]++;
}
long long query(long long x,int rk)
{
int u=0;long long ans=0;
for(int i=31;i>=0;i--)
{
int ch=(x>>i)&1;//cout<<u<<" "<<ch<<" "<<size[a[u][1]]<<" ";
if(!a[u][ch^1])u=a[u][ch];
else if(rk<=size[a[u][ch^1]])u=a[u][ch^1],ans|=1LL<<i;
else rk-=size[a[u][ch^1]],u=a[u][ch];
}
return ans;
}
long long getin()
{
long long x=0;char ch=getchar();
while(ch<'0'||ch>'9')ch=getchar();
while(ch>='0'&&ch<='9')x=x*10+ch-48,ch=getchar();
return x;
}
int main()
{
n=getin(),m=getin();m<<=1;
for(int i=1;i<=n;i++)x=getin(),s[i]=s[i-1]^x;
for(int i=0;i<=n;i++)ins(s[i]);
for(int i=0;i<=n;i++)q.push((Node){i,1,query(s[i],1)});
for(int i=1;i<=m;i++)
{
Node t=q.top();ans+=t.w;q.pop();//cout<<t.id<<" "<<t.rk<<" "<<t.w<<endl;
if(t.rk<n)q.push((Node){t.id,t.rk+1,query(s[t.id],t.rk+1)});
}
cout<<(ans>>1)<<endl;
}
by AlexSong @ 2024-01-29 11:46:17
@[AlexSong](/user/1004299) 这不就第一篇题解吗。。。不想好好调可以不调。。。
by Eirin_Yagokoro @ 2024-01-29 11:47:15
哦哦哦又在卷
by Wf_yjqd @ 2024-01-29 11:58:15
AC 了，trie 里有两步操作反了。
此帖结。
by Eirin_Yagokoro @ 2024-01-29 12:23:46