BZOJ

裸的线段树分治+线性基，就是跑的巨慢_(:з」∠)_ 。
不知道他们都写的什么=-=

//41652kb   11920ms
#include <map>
#include <cstdio>
#include <cctype>
#include <vector>
#include <algorithm>
#define BIT 30
#define gc() getchar()
#define MAXIN 500000
//#define gc() (SS==TT&&(TT=(SS=IN)+fread(IN,1,MAXIN,stdin),SS==TT)?EOF:*SS++)
typedef long long LL;
const int N=5e5+5;std::map<int,int> las;
char IN[MAXIN],*SS=IN,*TT=IN;
struct Base
{int x[BIT+1];void Insert(int v){for(int i=BIT; ~i; --i)if(v>>i&1)if(x[i]) v^=x[i];else {x[i]=v; break;}}void Query(){int res=0;for(int i=BIT; ~i; --i) res=std::max(res,res^x[i]);printf("%d\n",res);}
}base;
struct Segment_Tree
{#define ls rt<<1#define rs rt<<1|1#define lson l,m,ls#define rson m+1,r,rs#define S N<<2std::vector<int> vec[S];#undef Svoid Modify(int l,int r,int rt,int L,int R,int v){if(L<=l && r<=R) {vec[rt].push_back(v); return;}int m=l+r>>1;if(L<=m) Modify(lson,L,R,v);if(m<R) Modify(rson,L,R,v);}void Solve(int l,int r,int rt,Base b){for(std::vector<int>::iterator it=vec[rt].begin(); it!=vec[rt].end(); ++it) b.Insert(*it);if(l==r) {b.Query(); return;}int m=l+r>>1; Solve(lson,b), Solve(rson,b);}
}T;inline int read()
{int now=0;register char c=gc();for(;!isdigit(c);c=gc());for(;isdigit(c);now=now*10+c-48,c=gc());return now;
}int main()
{#define S 1,n,1const int n=read();for(int i=1; i<=n; ++i){int a=read();if(las[a]) T.Modify(S,las[a],i-1,a), las[a]=0;else las[a]=i;}for(std::map<int,int>::iterator it=las.begin(); it!=las.end(); ++it)if((*it).second) T.Modify(S,(*it).second,n,(*it).first);T.Solve(S,base);return 0;
}