CodeForces Round #173 (282E) - Sausage Maximization 字典树

#include
#include
#include
#include
#include
#include
#include
#define oo 1000000007
#define ll long long
#define pi acos(-1.0)
using namespace std;
struct node
{
       int son[2]; 
       ll w;
}p[10000005];
ll a[100005],totol,ans,_2jie[45];
int num;
void InsertToTrie(ll x)
{
       int h=0,i,t;
       for (i=40;i>=0;i--)
       {
             if (x & _2jie[i]) t=1;
                else t=0;
             if (!p[h].son[t]) p[h].son[t]=++num;
             h=p[h].son[t];
       }       
       p[h].w=x;
       return;
}
ll SerchMax(ll x)
{
       int h,i,t;
       h=0;
       for (i=40;i>=0;i--)
       {
             if (x & _2jie[i]) t=1;
                else t=0;
             if (p[h].son[1-t]) h=p[h].son[1-t];
                else h=p[h].son[t]; 
       }
       return p[h].w;
} 
int main()
{
       int i,n;
       ll prefix,postfix; 
       _2jie[0]=1;
       for (i=1;i<=40;i++) _2jie[i]=_2jie[i-1]*2;
       while (~scanf("%d",&n))
       {
             postfix=0;
             for (i=1;i<=n;i++) scanf("%I64d",&a[i]),postfix^=a[i]; 
             memset(p,0,sizeof(p));
             ans=postfix;
             num=0;
             prefix=0;
             InsertToTrie(0);
             for (i=1;i<=n;i++)
             {
                    prefix^=a[i];
                    InsertToTrie(prefix);
                    postfix^=a[i]; 
                    ans=max(ans,SerchMax(postfix)^postfix);
             }
             printf("%I64d\n",ans);    
       }
       return 0;
}